Chem 1b final round 2
A solution is made by diluting 20.0 mL of propanone (C3H6O) with water. The total volume of the solution is 300 mL. What is the percent by volume of propanone in the solution? Show your work. (3 points)
%(v/v) = 20.0mL propanone / 300mL x 100% = 6.67%
A gas with a volume of 20.0 liters at 760 torr will have what volume if the pressure changes to 380 torr? Solve to 3 significant digits. Show your work.
(1) P1 = 760 torr V1 = 20.0 liters P2 = 380 torr (2) V2 = X (3) P1V1 = P2V2 so (4) V2 = P1V1 / P2 (5) V2 = (760 torr)(20.0L)/(380 torr) = 40.0 L Torr/torr cancels out, leaving the final unit as L.
What is the molal freezing-point depression constant? (2 points)
The molal freezing-point depression constant is equal to the change in freezing point for 1-molal solution of a nonvolatile molecular solute.
What is percent yield? (2 points)
The percent yield is the ratio of the actual yield to the theoretical yield expressed as a percent.
What is the simplest alkyne? What is its common name? (2 points)
The simplest alkyne is ethyne (C2H2), which has the common name acetlyene.
What does the stability of a nucleus depend on? (2 points)
The stability of a nucleus depends on the ratio of neutrons to protons.
Calculate the mole fraction of each component in a solution of 1.5 mole C2H5OH and 6.8 mole H2O. Show your work.
X(C2H5OH) = 1.5 mol / (1.5 mol + 6.8 mol) = 0.18 X(H2O) = 6.8 mol / (1.5 mol + 6.8 mol) = 0.82
According to the Bronsted-Lowry theory, bases _____.
accept hydrogen ions
The _____ is the ratio of the concentration of the dissociated form of an acid to the concentration of the undissociated form.
acid dissociation constant (Ka)
A solution with a pH of less than 7 is considered _____.
acidic
When the [H+] is greater than [OH-]
acidic
A(n) _____ is two or more different molecular forms of the same element in the same physical state.
allotrope
A _____ is used to measure atmospheric pressure.
barometer
You can easily distinguish between the Arrhenius and Bronsted-Lowry definitions by the way a _____ is defined.
base
An alkane with one or more alkyl groups is called a _____.
branched-chain alkane
Strong acids _____ in water.
completely ionize
_____ is the process by which a compound separates into ions when in an aqueous solution.
dissociation
During the _____, heat is either released or absorbed.
formation of a solution
In reactions involving oxygen, a substance that undergoes oxidation _____ oxygen.
gains
identify the reactants and the products. hydrogen peroxide → water + oxygen
hydrogen peroxide is the reactant and water and oxygen are the product
Compounds that remove water from the air are known as _____.
hygroscopic hydrates
Law of conservation of energy
in any chemical or physical process, energy is neither created nor destroyed
An increase in the temperature of a contained liquid _____ the vapor pressure.
increases
The particles in all states of matter, including liquids, have _____.
kinetic energy
According to the _____ theory, all matter consists of tiny particles that are in constant motion.
kinetic molecular
In reactions involving oxygen, a substance that undergoes reduction _____ oxygen.
loses
A piece of silver has a heat capacity of 42.8 J/°C and a mass of 181 grams. Calculate the specific heat of silver.
m (Ag) = 181g ∆T = 1°C q = 42.8J C (Ag) = q / ( m * ∆T) = 42.8 J / (181g * 1°C) = 0.236J/(g*°C)
Liquids are _____ than gases.
more dense
Oxidation-reduction reactions are also known as _____ reactions.
redox
The smallest group of particles within a crystal that retains the geometric shape of the crystal is the _____.
unit cell
The conversion of a liquid to a gas or vapor is _____.
vaporization
The ease of evaporation measures the _____ of a liquid.
volatility
The particle arrangement of liquids prevents pressure increases from affecting the _____.
volume
Aqueous solution
water that contains dissolved substances
A _____ reacts with water to form the conjugate acid of the base and hydroxide ions.
weak base
Complete the equation: ΔHvap =_____. (2 points)
ΔH cond
How many moles of sulfuric acid are required to neutralize 0.70 mol of sodium hydroxide? (2 points)
0.35 mol of sulfuric is required to neutralize 0.70 mol of sodium hydroxide.
the balanced equation gives us a ratio of reactants and products. Use the balanced equation provided N2(g) + 3H2(g) --> 2NH3(g), Moles N2
1
the balanced equation gives us a ratio of reactants and products. Use the balanced equation provided N2(g) + 3H2(g) --> 2NH3(g), Number of molecules H2
1
How many moles of CaCl2 are in 2.26 L of 0.298 M CaCl2? Show your work.
2.26L x 0.298 mol CaCl2/1L = 0.674 mol CaCl2
the balanced equation gives us a ratio of reactants and products. Use the balanced equation provided N2(g) + 3H2(g) --> 2NH3(g), Mass N2
28.01g/mol
Write balanced equations for the following reactions. Silver(I) nitrate plus zinc yields zinc nitrate plus silver.
2AgNO3 + Zn --> Zn(NO3)2 + 2Ag
When 5.00 g of copper react with excess silver nitrate, silver metal and copper (II) nitrate are produced. Write the balanced equation. What is the theoretical yield of silver in this reaction? (5 points)
2AgNO₃ + Cu → Cu(NO₃)₂ + 2Ag 5.00g Cu X 1 mol Cu / 63.546g Cu X 2 mol Ag / 1 mol Cu X 107.8682g Ag / 1 mol Ag = 17.0g Ag The theoretical yield of silver in this reaction is 17.0g Ag.
Rust (Fe2O3) is produced when iron (Fe) reacts with oxygen (O2). Calculate the number of grams of rust produced when 12 gram of iron react with oxygen.
4Fe + 3O2→ 2Fe2O3 12.0g Fe X 1 mol Fe / 55.847g Fe X 2 mol Fe2O3 / 4 mol Fe X 159.6922g Fe2O3 / 1 molFe2O3 = 17.1567g Fe2O3 = 17g Fe2O3
Define a Lewis base. (2 points)
A Lewis base is a substance that can donate a pair of electrons to form a covalent bond.
What is a beta particle. (2 points)
A beta particle is an electron resulting from the breaking apart of a neutron in an atom.
Define "catalyst."
A catalyst is a substance that speeds up the reaction but is not used up in the reaction. A catalyst is neither a reactant nor a product, so its formula is written above the arrow in a chemical equation.
Define neutral solution. (2 points)
A neutral solution is any aqueous solution in which H+ and OH- are equal.
What is a suspension? (2 points)
A suspension is a mixture from which particles settle upon standing.
What is a spectator ion?
An ion that appears on both sides of an equation and is not directly involved in the reaction
Define oxidation number. (2 points)
An oxidation number is a positive or negative number assigned to an atom to indicate its degree of oxidation or reduction.
Define unsaturated compound. (2 points)
An unsaturated compound is an organic compound that contains double or triple carbon-carbon bonds.
An _____ is a hydrogen-containing compound that dissociates to yield hydrogen ions in aqueous solutions.
Arrhenius acid
A copper coin is heated and placed in a foam-cup calorimeter containing 32.0 mL of water at 22.0°C. The water reaches a maximum temperature of 24.0°C. How many joules of heat are released by the coin? Show your work. (4 points)
C = 4.18 J / (g x °C) V = 32.0mL m = 32.0 g ΔT = 24.0°C - 22.0°C = 2°C ΔH = -(32.0g)(4.18J/(g x °C))(2°C) = -270J
Define efflorescence. (2 points)
Efflorescence is the property of a hydrate to lose its water of hydration when exposed to air with a vapor pressure higher than the pressure of water vapor in the air.
Define effusion.
Effusion is gas escaping through a tiny hole in its container.
What are two methods that can be used to measure pH? (2 points)
Either acid-base indicators or pH meters can be used to measure pH.
How do energy changes occur? (3 points)
Energy changes occur as either heat transfer or work, or a combination of both.
The number of atoms and the number of molecules are _______________ on reactant and product sides of the equation.
Equal
You may eat an apple during an experiment.
False
Define half-life. (2 points)
Half-life is the time required for one-half of the nuclei in a radioisotope sample to decay to products.
Define hydronium ion (H3O+). (2 points)
Hydronium ion is the ion that forms when a water molecule gains a hydrogen atom.
In a chemical equation, how can the enthalpy change for the reaction be written? (2 points)
In a chemical equation, the enthalpy change for the reaction can be written as either a reactant or a product.
What happens in a nuclear chain reaction? (3 points)
In a nuclear chain reaction, some of the emitted neutrons react with other fissionable atoms, which emit neutrons that react with still more fissionable atoms.
What is the standard atmospheric pressure in fair weather at sea level? (2 points)
In fair weather at sea level, the atmospheric pressure is sufficient to support a mercury column 760 mm Hg, 1 atm, or 101.3 kPa.
In general, what do acids and bases produce when they react? (2 points)
In general, acids and bases react to produce a salt and a water.
In hydrates, why is the water easily lost and regained? (2 points)
In hydrates, the water is easily lost and regained because the forces holding the water molecules in hydrates are not very strong.
How much 0.50 M NaCl solution should be diluted to produce 6.5 L of a 0.15 M NaCl solution? Show your work.
Initial Molarity x Initial Volume = Final Molarity x Final Volument 0.5M NaCl x ? Volume = 0.15M NaCl x 6.5L Solving for Initial Volume = 1.95L
Define ionizing radiation. (2 points)
Ionizing radiation is radiation emitted by radioisotopes because it has enough energy to knock electrons off some atoms of a bombarded substance, producing ions.
What is the freezing point of a 0.800m aqueous solution of glucose, given that Kf for water is 1.86°C/m? Show your work. (3 points)
Kf x m = 1.86 C/m x 0.800m = 1.49 C 0.00°C - 1.49C = -1.49°C
Define kinetic theory. (2 points)
Kinetic Theory states all matter consists of tiny particles that are in constant motion.
How much heat (in kJ) is absorbed when 60.5 g H2O(l) at 100°C and 101.3kPa is converted to H2O(g) at 100°C and 101.3 kPa? (ΔHvap = 40.7 kJ/mol)
Knowns: Initial and final conditions are 100⁰C and 101.3 kPa mass of liquid water converted to steam = 60.5 g ΔHvap = 40.7 kJ/mol Unknown: ΔH = ? kJ ΔH = 60.5g H2O(l) x 1 mol H2O(l) / 18.0g H2O(l) x 40.7 kJ / 1 mol H2O(l) = 137 kJ
How many grams of ice at 0°C will melt if 15.0 kJ of heat are added?
Knowns: Initial and final temperatures are 0°C ΔHfus = 6.01 kJ/mol ΔH = 15.0 kJ Unknown: mice = ? g 1 mol H2O(s) / 6.01 kJ 18.0g H2O(s) / 1 mol H2O(s) mice = 15.0 kJ x 1 mol H2O(s) / 6.01 kJ x 18.0g H2O(s) / 1 mol H2O(s) = 44.9 g H2O(s)
Define molality. (2 points)
Molality is the number of moles of solute dissolved in 1 kilogram of solvent and known as molal concentration.
Define molar heat of condensation. (2 points)
Molar heat of condensation is the amount of heat released when one mole of a vapor condenses at its normal boiling point.
Define molar heat of fusion. (2 points)
Molar heat of fusion is the heat absorbed by one mole of a solid substance as it melts to a liquid at a constant temperature.
Write the equation for finding the molarity of a solution. (2 points)
Molarity M = moles of solute/liters of solution
Within how many pH values do most indicators operate? (2 points)
Most indicators operate within 2 pH units.
For the following reaction, identify the oxidized element, the reduced element, the oxidizing agent, and the reducing agent. You will not use all of the terms given. 2Na(s) + S(s) -->Na2S(s) Oxidized
Na
Write the spectator ions for the reaction: H2SO4(aq) + NaOH(aq) → Na2SO4(aq) + H2O(l)SO4²⁻)
Na⁺
Define neutron absorption. (2 points)
Neutron absorption is a process that decreases the number of slow-moving neutrons. Control rods, made of materials such as cadmium, are used to absorb neutrons.
Define nuclear force. (2 points)
Nuclear force is an attractive force that acts between all nuclear particles that are extremely close together, such as protons and neutrons in a nucleus.
What is nuclear radiation? (2 points)
Nuclear radiation is the rays and particles emitted from a radioactive source.
For the following reaction, identify the oxidized element, the reduced element, the oxidizing agent, and the reducing agent. You will not use all of the terms given. 4Al(s) + 3O2(g) Al2O3(s) Oxidizing agent
O2
In the reaction C2H4 + 3O2 → 2CO2 + 2H2O, which is the limiting reagent if 2.70 mol C2H4 reacts with 6.30 mol O2? (2 points)
O2 is the limiting reagent because 2.70 mol C2H4 X 3 mol O2 / 1 mol C2H4 = 8.1 mol O2. Since we only have 6.30 mol O2 we are limited by the 6.30 mol O2 in how much product we can make.
According to Arrhenius, bases produce _____ ions in aqueous solution.
OH-
Use the changes in oxidation numbers to identify which atoms are oxidized and which are reduced for each reaction in questions 13-14. Label your answers clearly. (4 points, 2 points each) 2H2(g) + O2(g) 2H2O(l) Oxidized = Reduced =
Oxidized = Hydrogen (H2) Reduced = Oxygent (O2)
Identify which atoms are oxidized and which are reduced, then identify the oxidizing agent and the reducing agent for each reaction in questions 15-16. Label your answers clearly. (8 points, 4 points each) PbS(s) + O2(g) PbO(s) + SO2(g) Oxidized = Reduced = Oxidizing agent = Reducing agent =
Oxidized = Sulfur (S) Reduced = Oxygen (O2) Oxidizing agent = Oxygen (O2) Reducing Agent = PbS
Determine the oxidation number of chlorine for each of the substances and list the rules that apply in questions 8-11. (8 points, 2 points each) Cl2O
Oxygen = -2 Cl = +1 rules 3 and 5
Determine the oxidation number of each element in NO3-.
Oxygen has a -2 charge and we have three of them so -6 for all the oxygens but our total charge is -1 so Nitrogen = +5
A gas has a solubility in water at 0°C of 7.0 g/L at a pressure of 3.0 atm. What pressure is needed to produce an aqueous solution containing 12 g/L of the same gas at 0°C? Show your work.
S1 = 7.0 g/L P1 = 3.0 atm S2 = 12 g/L P2 = ? (7.0 g/L)/(3.0 atm) = (12 g/L)/P2 P2 = (12 g/L)(3.0 atm)/(7.0 g/L) P2 = 5.1 atm
Write the equation for the ion-product constant for water [Kw]. (2 points)
Kw = [H+] x [OH-] = 1.0 x 10-14
Weak acids _____ in water.
slightly ionize
What behavior of particles determines the physical properties of liquids? (3 points)
The behavior of particles that determine the physical properties of liquids is the fact that they can move around each other to change shape but are still held together enough to hold the same volume.
What is the bond angle of the water molecule?
The bond angle of the water molecule is approximately 105 degrees.
What is the bond angle of the water molecule? (2 points)
The bond angle of the water molecule is approximately 105 degrees.
How does the presence of salts and acids accelerate the corrosion of metals? (3 points)
The presence of salts and acids accelerates corrosion by producing conductive solutions that make electron transfer easier.
What are three colligative properties of solutions? (3 points)
Three colligative properties of solutions are vapor-pressure lowering, freezing-point depression, and boiling-point elevation.
Conjugate acid-base pair
Two ions or molecules related by the loss or gain of one hydrogen ion.
How should the volume of a liquid in a graduated cylinder be read?
at the bottom of the meniscus
How many grams of sodium bromide must be dissolved in 500.0 g of water to produce a 0.600 molal solution? Show your work.
mass of water = 500.0 g = 0.5000 kg solution concentration = 0.600m molar mass of NaBr = 102.894 g/mol mass of solute = ? g NaBr 0.600 mol NaBr / 1.000 kg H2O 102.894 g/mol / 1 mol NaBr 0.5000 kg H2O x 0.600 mol NaBr / 1.000 kg H20 x 102.894 g NaBr / 1 mol Na Br = 30.9 g NaBr
Nonpolar solvents such as gasoline, dissolve _____ compounds.
nonpolar
The inward force or pull that tends to minimize the surface area of a liquid is the _____.
surface tension
Solvent
the dissolving medium
Which of the following descriptions of gas burner flame color air vent status, and degree of air mixing are realistic?
yellow flame, closed air vents, poor mixing of air
14. How many liters of water vapor are formed when 1.2 L of oxygen react with acetylene?
1.2L O2 X 1 mol O2 / 22.4 L O2 X 2 mol H2O / 5 mol O2 X 22.4L H2O / 1 mol H2O =0.48L H2O
Write a balanced equation for the following reaction: hydrogen plus oxygen yields water.
2 H2 + O2 --> 2 H2O
For the reaction of aluminum sulfate solution with ammonium hydroxide solution, Complete ionic equation
2Al³⁺ + 3SO4²⁻ + 6NH4⁺ + 6OH⁻ → 2Al(OH)3(s) + 6NH4⁺ + 3SO4²⁻
In sulfuric acid (aqueous solution), potassium iodide reacts according to the following equation. H2SO4(aq) + KI(s) K2SO4(aq) + I2(g) + SO2(g) + H2O(l) Use this information to answer questions 10-12. What is the oxidation half-reaction? (3 points)
2I- è I2 + 2e-
Use coefficients to balance the following chemical equations. iron + oxygen → iron (III) oxide
4 Fe + 3 O2 --> 2 Fe2O3
the balanced equation gives us a ratio of reactants and products. Use the balanced equation provided N2(g) + 3H2(g) --> 2NH3(g), Volume at STP NH3
44.8L
How many liters of CO2 are produced when 5.20 L of C2H2 are burned in oxygen?
5.20 L C2H2 X 1 mol C2H2 / 22.4 L C2H2 X 4 mol CO2 / 2 mol C2H2 X 22.4L CO2 / 1 molCO2 = 10.4L CO2
the balanced equation gives us a ratio of reactants and products. Use the balanced equation provided N2(g) + 3H2(g) --> 2NH3(g), Mass H2
6.06g/mol
the balanced equation gives us a ratio of reactants and products. Use the balanced equation provided N2(g) + 3H2(g) --> 2NH3(g), Volume at STP H2
67.2L
Define "balanced equation."
A balanced equation is an equation for a chemical reaction in which the number of atoms for each element in the reaction and the total charge is the same for both the reactants and the products.
What is a skeleton equation?
A skeleton equation is a chemical equation that does not indicate the relative amounts of the reactants and products.
When is a solution considered a saturated solution? (3 points)
A solution is considered a saturated solution when it contains the maximum amount of solute for a given amount of solvent at a constant temperature and pressure.
Identify the acid, conjugate acid, base, and conjugate base in the following equation. Label your answers to correspond with each part as shown in the equation (i.e., A, B, C, D). (4 points, 1 point each) (A) NH3(aq) + (B) HOH(l) (C) NH4+(aq) +(D) OH-(aq)
A. base B. acid C. conjugate acid D. conjugate base
How are acids and bases classified as either strong or weak?
Acids and bases are classified as strong or weak based on the degree to which they ionize in water. In general, a strong acid is completely ionized in aqueous solution.
For the following reaction, identify the oxidized element, the reduced element, the oxidizing agent, and the reducing agent. You will not use all of the terms given. 4Al(s) + 3O2(g) Al2O3(s) Reducing agent
Al
Identify the Lewis acid and the Lewis base in each of the reactions in questions 11-14. (8 points, 2 points each) AlCl3 + Cl- AlCl4-
AlCl3 = Lewis acid Cl = Lewis base
Define alkyne. (2 points)
An alkyne is a hydrocarbon that contains one or moe carbon-carbon triple covalent bonds.
How are oxidation and reduction defined in terms of a change in oxidation number? (4 points)
An increase in the oxidation number of an atom or ion indicates oxidation whereas a decrease in the oxidation number of an atom or ion indicates reduction.
Balance the following redox equation by using the oxidation-number-change method. Ba(ClO3)2-->BaCl2 + O2
Ba(ClO3)2(s) --> BaCl2(s) + 3O2(g)
Define boiling-point elevation. (2 points)
Boiling-point elevation is the difference in temperature between the boiling point of a solution and the boiling point of the pure solvent.
Ammonia is a base under the _____ definition of a base.
Bronsted-Lowry
Identify the Lewis acid and the Lewis base CN- + H+ HCN
CN = Lewis base H = Lewis acid
When 16.5 g of calcium carbonate react with an excess of hydrochloric acid, calcium chloride, carbon dioxide, and water vapor are produced. Write the equation. What is the theoretical yield of carbon dioxide? (5 points)
CaCO₃+ 2HCl → CaCl₂ + CO₂ + H₂O 16.5g CaCO₃ X 1 mol CaCO₃ / 100.0869g CaCO₃ X 1 mol CO₂ / 1 mol CaCO₃ X 44.01g CO₂ / 1 mol CO₂ = 7.26g CO₂ The theoretical yield of carbon dioxide is 7.26g.
State Charles's Law. (2 points)
Charles's Law states that a volume of a fixed mass of gas is directly proportional to its Kelvin temperature if the pressure is kept constant.
Determine the oxidation number of chlorine for each of the substances and list the rules that apply in questions 8-11. (8 points, 2 points each) Cl2
Cl oxidation number is 0 by rule 4.
1. Ions, atoms, small molecules 2. Large particles or aggregates 3. 1-1000nm 4. Exhibits Tyndall effect. 5. Stable, does not separate 6. Particles not retained on filter 7. Heterogeneous
Complete the Properties of Solutions, Colloids, and Suspensions Chart below. Number your answers in the same order as shown in the table below (1-7). Click the Lesson 15.3 Quiz - Properties of Solutions, Colloids, and Suspensions Chart Worksheet Word document to download a printable version of the chart. You can write your answers on the printed version, then use it to complete the chart below. (7 points, 1 point each)
What is compressibility? (2 points)
Compressibility is a measure of how much the volume of matter decreases under pressure Compressibility is a measure of how much the volume of matter decreases under pressure.
Define constitutional isomers. (2 points)
Constitutional isomers are compounds that have the same molecular formula, but the atoms are joined together differently.
Define cycloalkane. (2 points)
Cycloalkane is a cyclic hydrocarbon that contains only a single bond and is therefore saturated.
Define diffusion.
Diffusion is the tendency of molecules to move towards areas of lower concentration until the concentration is uniform throughout.
Define dilution. (2 points)
Dilution is the process of preparing a less-concentrated solution from a more concentrated one by adding solvent.
What happens to the energy of the universe during a chemical or physical process? (2 points)
During a chemical or physical process the energy of the universe remains unchanged.
What happens to the energy of the universe during a chemical or physical process?
During any chemical or physical process, the energy of the universe remains unchanged.
give an example for each of these colloid systems. Solid-gas
Dust in air
Write the skeleton equation for the following: iron plus oxygen yields iron (III) oxide.
Fe + O2 --> Fe2O3
Iron oxide reacts with carbon monoxide to yield iron and carbon dioxide. Write the balanced formula.
Fe₂O₃ + 3CO → 2Fe + 3CO₂
Compare fission and fusion reactions.
Fission reactions compare to fusion reactions because fusion reactions, in which small nuclei combine, release much more energy than fission reactions, in which large nuclei split apart and form smaller nuclei. Fusion reactions occur only at very high temperatures
give an example for each of these colloid systems. Liquid-gas
Fog and aerosol
When does fusion occur? (3 points)
Fusion occurs when nuclei combine to produce a nucleus of greater mass.
Why are gases easily compressed? (3 points)
Gases are easily compressed because of the space between the particles in a gas.
State Gay-Lussac's Law. (2 points)
Gay-Lussac's Law states the pressure of a gas is directly proportional to the Kelvin temperature if the volume is constant.
Why does granulated sugar dissolve faster than a cube of sugar? (3 points)
Granulated sugar dissolves faster than a cube of sugar because of the smaller surface area. Since the process of dissolves occurs at the surface of the solute, sugar, a smaller surface area will dissolve faster than a larger one.
_____ metal hydroxides are not very soluble in water.
Group 2A
According to Arrhenius, acids produce _____ ions in aqueous solution.
H+
Identify the Lewis acid and the Lewis base in each of the reactions in questions 11-14. (8 points, 2 points each) H+ + H2O H3O+
H+ = Lewis acid H2O = Lewis base
Write balanced equations for the following reactions. Hydrogen plus chlorine yields hydrochloric acid.
H2 + Cl2 --> 2 HCl
Write the skeleton equation for the following questions. hydrogen peroxide → water + oxygen
H2O2 --> H2O + O2
Write a balanced complete ionic equation for the reaction: H2SO4(aq) + NaOH(aq) → Na2SO4(aq) + H2O(l)
H2SO4(aq) + 2NaOH(aq) → Na2SO4(aq) + 2H2O(l) 2H + SO4 + 2Na + 2OH → 2Na + SO4 + 2H2O(l) 2H⁺ + SO4²⁻ + 2Na⁺ + 2OH⁻ → 2Na⁺ + SO4²⁻ + 2H2O(l)
Identify the Lewis acid and the Lewis base HCO3- + H+ H2CO3
HCO3 = Lewis base H = Lewis acid
Write balanced equations for the following reactions. Hydrochloric acid plus sodium hydroxide yields sodium chloride plus water.
HCl + NaOH --> NaCl + H2O
Define Henry's Law. (2 points)
Henry's Law states at a given temperature the solubility of a gas in a liquid is directly proportional to the pressure of the gas above the liquid.
State Hess's law of heat summation. (2 points)
Hess's law of heat summation states that if you add two or more thermochemical equations to give a final equation, then you can also add the heats of reaction to give the final heat of reaction.
Water is decomposed to yield hydrogen gas and oxygen gas in an endothermic reaction. How many kilojoules of heat are required to decompose 114 mol H2O? 2H2O + 571.6 kJ-->2 H2 + O2. Show your work. (3 points) Use the word "Delta" to represent the Δ symbol where needed.
Knowns: amount of H2O(l) that decomposes = 114 mol ΔH = 571.6 kJ for 2 mol H2O Unknown: ΔH = ?kJ for 114 mol H2O 571.6kJ/2 mol H2O ΔH = 114 mol H2O(l) x 571.6kJ/2mol H2O(l) = 32,581.2kJ = 32,600kJ
The equation for dissociation constant of acids is Ka = [H+][A-] / [HA] with [H+] representing the hydrogen ion, [A-] as the acid ion, and [HA] as the undissociated acid molecule. Use sample problem 18.6 on page 645 in the textbook to answer questions 2-3. (8 points, 4 points each) A 0.725 M solution of a weak acid has [H+] = 5.23 × 10-6 M. What is the value of Ka for this acid? Show your work.
Knowns: weak acid = 0.725M [H+] = 5.23 x 10-6M Unknown: Ka = ? Ka = [H+][A-]/[HA] = 5.23 x 10-6 x 5.23 x 10-6 / 0.72499477 = 3.77 x 10-11
Use the changes in oxidation numbers to identify which atoms are oxidized and which are reduced for each reaction in questions 13-14. Label your answers clearly. (4 points, 2 points each) 2KNO3(s) 2KNO2(s) + O2 Oxidized = Reduced =
Oxidized = Oxygen (O2) Reduced = Nitrogent (N2)
Define partial pressure.
Partial pressure is the contribution each gas in a mixture makes to the total pressure exerted by that gas.
Using the equation on page 524 in the textbook, what is the percent by mass of the water in Epsom salts (MgSO4 7H2O)? Show your work. (4 points)
Percent by mass of H2O = mass of water/mass of hydrate x 100% = 18.01528g/mol/246.47296g/mol x 100% = 7.31%
What is percent by volume? (2 points)
Percent by volume of a solution is the ratio of the volume of solute to the volume of solution.
Which of the following is an appropriate technique to use when pouring liquids?
Pour the liquid slowly down a glass stirring rod into a beaker.
Write the general word description of a reaction.
Reactants yield products
Which of the following is an appropriate procedure to follow when using a balance?
Remember to zero the balance.
Determine the oxidation number of each element and list the rules that apply in questions 4-7. (12 points, 3 points each) NO3-
Rules 3 and 6. Oxygen is -2 and nitrogen is +5
Sulfur dioxide reacts with oxygen to produce sulfur trioxide. Write the equation. Identify the limiting reagent when 20.0 g of SO2 react with 15.6 g of O2. (5 points)
SO₂ + O2 → SO₃ 1 - S - 2 4 - O - 3 2SO₂ + O2 → 2SO₃ 20.0g SO₂ X 1 mol SO₂ / 64.066g SO₂ X 1 mol O₂ / 2 mol SO₂ X 32g O₂ / 1 mol O₂ = 4.99g O₂ SO₂ is the limiting reagent because only 4.99g O₂ would react with the 20g SO₂ given.
Write balanced equations for the following reactions. Ammonium carbonate yields ammonia plus carbon dioxide plus water.
(NH4)2CO3 --> 2 NH3 + CO2 + H2O
Calculate [H+] for each solution in questions 14-15. Show your work. (6 points, 3 points each) pH = 12.83
1.479 x 10-13
Define equivalence point. (2 points)
The equivalence point is the point at which neutralization occurs.
Flammable liquids may be heated using a hot plate.
True
What is the theoretical point at which substances should have no kinetic energy known as? List the temperature in Kelvin and in Celsius.
absolute zero C, and 273 K
[H+] = 2.0 × 10-2 M
acidic
In _____, the cations and anions of a dissociated salt remove hydrogen ions from or donate hydrogen ions to water.
salt hydrolysis
A balloon has a volume of 6.25 L at 453 kPa. What would the volume of this balloon be at 325 kPa? Show your work. (4 points)
(1) P1 = 453kPa V1 = 6.25L P2 = 325kPa (2) V2 = X (3) P1V1=P2V2 so (4) V2 = P1V1/P2 (5) V2 = (453kPa)(6.25L)/(325kPa) = 8.71L
At 44°C, the volume of a balloon is 2.53 L. If the balloon is cooled to 21°C, what will the new volume of the balloon be? Show your work. (4 points)
(1) V1 = 2.53L T1 = 44C + 273 = 317K T2 = 21C + 273 = 294K (2) V2 = X (3) V1/T1 = V2/T2 so (4) V2 = V1T2/T1 (5) V2 = (2.53L)(294K)/(317K) = 2.35L
Using the IUPAC method of naming alkanes, each will end in _____.
-ane
Complete the equation: ΔHfus = _____. (2 points)
-ΔHsolid
the balanced equation gives us a ratio of reactants and products. Use the balanced equation provided N2(g) + 3H2(g) --> 2NH3(g), Number of molecules N2
1
the balanced equation gives us a ratio of reactants and products. Use the balanced equation provided N2(g) + 3H2(g) --> 2NH3(g), Number of molecules NH3
1
you have one mole of sugar, How many grams of sugar are present?
1 mol C6H12O6 X 180.16g C6H12O6 / 1 mol C6H12O6 = 180.16g C6H12O6
How many moles of Fe are produced when 1.8 moles of Fe2O3 react with CO (refer to page 413 in the textbook)?
1.8 mol Fe2O3 X 2 mol Fe / 1 mol Fe2O3 = 3.6 mol Fe
the balanced equation gives us a ratio of reactants and products. Use the balanced equation provided N2(g) + 3H2(g) --> 2NH3(g), Moles NH3
2
What is the percent yield if 4.65 g of copper are produced when 1.87 g of aluminum react with an excess of copper (II) sulfate? Write the equation. (5 points)
2Al + 3CuSO₄ = Al₂(SO₄)₃ + 3Cu Theoretical yield of Cu = 1.87g Al X 1 mol Al / 26.981539g Al X 3 mol Cu / 2 mol Al X 63.546g Cu / 1 mol Cu = 6.61g Cu Percent yield = Actual Yield / Theoretical Yield X 100⁒ = 4.65g Cu / 6.61g Cu X 100⁒ = 70.4%
How many moles of CO are required to produce 7.5 mol of CO2?
7.5 mol CO2 X 3 mol CO / 3 mol CO2 = 7.5 mol CO
A 250 mL sample of oxygen is collected over water at 25°C and 760.0 torr pressure. What is the pressure of the dry gas alone? (Vapor pressure of water at 25°C = 23.8 torr)
760 torr - 23.8 torr = 736.2 torr this is because of Dalton's Law of Pressure which states the Total Pressure = Pressure of Gas + Presssure of Water
What is a gamma ray? (2 points)
A gamma ray is a high-energy photon emitted by a radioisotope.
What is an alkene? (2 points)
An alkene is a hydrocarbon that contains one or more carbon-carbon double covalent bonds.
An _____ is a compound that dissociates to yield hydroxide ions in aqueous solutions.
Arrhenius base
Assuming nothing else changes, what happens to the pressure of a gas in a rigid container if you add more gas? (3 points)
Assuming nothing else changes, if you add more gas to a rigid container with gas inside the pressure increases.
What is radioactivity also known as? (2 points)
Radioactivity is also known as radioactive decay.
Define self-ionization of water. (2 points)
Self-ionization of water is the reaction in which water molecules produce ions.
What is the difference between monoprotic acids, diprotic acids, and triprotic acids? (3 points)
The difference between monoprotic acids, diprotic acids and triprotic acids is that they vary in the number of hydrogens that can form hydrogen ions. Mono means one, di means two and tri means three so that is the number of hydrogens the respective acids have that can form hydrogen ions.
Conjugate acid
The ion or molecule formed when a base gains a hydrogen ion.
Define mole ratio.
a conversion factor derived from the coefficients of a balanced chemical equation interpreted in terms of moles.
Which of the following types of flame is probably the best for most laboratory work?
a light blue, cone-shaped flame
Concentration
a measure of the amount of solute that is dissolved in a given quantity of solvent
Define concentration.
a measure of the amount of solute that is dissolved in a given quantity of solvent
The theoretical point at which substances should have no kinetic energy is known as _____.
absolute zero
The ____ solid lacks an ordered internal structure, like rubber, asphalt, or plastic.
amorphous
How did Lewis define an acid and a base?
an acid accepts a pair of electrons whereas a base donates a pair of electrons during a reaction.
What is a net ionic equation?
an equation for a reaction in solution that shows only those particles that are directly involved in the chemical change.
What is a complete ionic equation?
an equation that shows dissolved ionic compounds as dissociated free ions.
Define hydrocarbon.
an organic compound that contains only H and C
The _____ is the result of the collisions of atoms and molecules in air with objects.
atmospheric pressure
At any given temperature, the particles of all substances, regardless of the physical states, have the same _____ energy.
average kinetic
A solution with a pH of more than 7 is considered _____.
basic
When the concentration of [OH-] is greater than [H+]
basic
[H+] = 6.0 × 10-10 M
basic
[OH-] = 3.0 × 10-2 M
basic
What equipment is essential for filtering a solid from a liquid?
beaker, funnel, filter paper, stirring rod, iron ring and stand
Because C has 4 valence electrons, a carbon atom always forms four _____.
covalent bonds
A group of compounds forms a _____ if there is a constant increment of change in molecular structure form from one compound in the series to the next.
homologous series
Calcium chloride is used in a _____ pack.
hot
A compound that contains water of hydration is called a(n) _____.
hydrate
A _____ is an organic compound that contains only H and C.
hydrocarbon
Vapor pressure is measured by a _____.
manometer
Define calorimetry.
the measurement of the heat transfer into or out of a system for chemical and physical processes.
Molarity (M)
the number of moles of solute dissolved in one liter of solution
System
the part of the universe on which you focus your attention
Solvation
the process by which the positive and negative ions of an ionic solid become surrounded by solvent molecules
Thermochemistry
the study of energy changes that occur during chemical reactions and changes in state
you have one mole of sugar, C6H12O6. How many molecules of sugar are present?
1 mol C6H12O6 X 6.02 x 10²³ particles / 1 mol = 6.02 X 10²³ molecules C6H12O6
List three reasons for percent yields to be less than 100%. (3 points)
1) Impure reactants and competing side reactions may cause unwanted products to form. 2) Actual yield can also be lower than the theoretical yield due to a loss of product during filtration or in transferring between containers 3) If reactants or products have not been carefully measured, a percent yield of 100 percent is unlikely.
Determine if 2-methylpropane has an asymmetric carbon. (2 points)
2-methylpropane has a symmetric carbon so it does not have asymmetric carbon.
Write the net ionic equation for the reaction: H2SO4(aq) + NaOH(aq) → Na2SO4(aq) + H2O(l)
2H⁺ + SO4²⁻ + 2Na⁺ + 2OH⁻ → 2Na⁺ + SO4²⁻ + 2H2O(l) 2H⁺ + 2OH⁻ → 2H2O(l)
In an airbag, sodium azide (NaN3(s)) decomposes into sodium metal and nitrogen gas. How many grams of sodium azide must decompose to form 20.0 g of nitrogen gas?
2NaN3(s) → 2Na(s) + 3N2(g) 20.0g N2 X 1 mol N2 / 28.02g N2 X 2 mol NaN3 / 3 mol N2 X 65.009869g NaN3 / 2 molNaN3 = 30.934984g NaN3 = 30.9g NaN3
Balance each redox equation by using the oxidation-number-change method in questions 6-7. (6 points, 3 points each) PbS(s) + O2(g) PbO(s) + SO2(g)
2PbS(s) + 3O2(g) --> 2PbO(s) + 2SO2(g)
the balanced equation gives us a ratio of reactants and products. Use the balanced equation provided N2(g) + 3H2(g) --> 2NH3(g), Moles H2
3
Determine if 3-methylpentane has an asymmetric carbon. (2 points)
3-methylpentane has a symmetric carbon so it does not have an asymmetric carbon.
How many liters of oxygen are required to burn 3.50 L of acetylene?
3.50 L C2H2 X 1 mol C2H2 / 22.4 L C2H2 X 5 mol O2 / 2 mol C2H2 X 22.4L O2 / 1 mol O2 =8.75L O2
the balanced equation gives us a ratio of reactants and products. Use the balanced equation provided N2(g) + 3H2(g) --> 2NH3(g), Mass NH3
34.06g/mol
Define colloid. (2 points)
A colloid is a heterogeneous mixture containing particles that range in size from 1nm to 1000nm.
What is the difference between a combination reaction and a combustion reaction?
A combination reaction produces a certain substance. A combustion reaction is a vigorous reaction, usually a combination with oxygen, that is accompanied by the production of light and/or heat.
When does a dynamic equilibrium exist? (3 points)
A dynamic equilibrium exists when an action that is reversible occurs.
Define a half-reaction. (2 points)
A half-reaction is an equation showing just the oxidation or just the reduction that takes place in a redox reaction.
How does a nonvolatile solute lower vapor pressure? (3 points)
A nonvolatile solute lowers vapor pressure because ions are surrounded by layers of associated water molecules. The formation of these shells of water of solvation reduces the number of solvent molecules that have enough kinetic energy to escape as vapor. Therefore, the solution has a lower vapor pressure than the pure solvent at the same temperature.
Define nuclear equation. (2 points)
A nuclear equation is a representation of a nuclear reaction; the symbols of the reactants are connected by an arrow with the symbols of the products.
What is a positron? (2 points)
A positron is a particle with the mass of an electron but a positive charge.
What is a precipitation reaction?
A precipitation reaction refers to the formation of an insoluble salt when two solutions containing soluble salts are combined.
Define saturated compound. (2 points)
A saturated compound is an organic compound that contains the maximum number of hydrogen atoms per carbon atom.
When is a solution considered an unsaturated solution? (3 points)
A solution is considered an unsaturated solution when it contains less solute than a standard solution at a given temperature and pressure.
Amphoteric
A substance that can act as either an acid or a base.
In reactions involving oxygen, what happens to a substance that undergoes oxidation? What happens to a substance that undergoes reduction?
A substance that undergoes oxidation gains oxygen and loses electrons. A substance that undergoes reduction loses oxygen and gains electrons
What is a supersaturated solution and how can you make it? (3 points)
A supersaturated solution contains more solute than it can theoretically hold at a given temperature. You can make a supersaturated solution by creating a saturated solution at a higher temperature and then letting it cool to a lower temperature where if you had made the saturated solution at the lower temp it would not have had as high amount of solute per solvent to become saturated.
How does a suspension differ from a solution?
A suspension differs from a solution because the particles of a suspension are much larger and do not stay suspended indefinitely.
How does a suspension differ from a solution? (3 points)
A suspension differs from a solution because the particles of a suspension are much larger and do not stay suspended indefinitely.
Define thermochemical equation. (2 points)
A thermochemical equation is a chemical equation that includes the enthalpy change.
Define alpha particle. (2 points)
Alpha particles are helium nuclei and each one contains two protons, two neutrons, and has a double positive charge.
When do real gases differ most from an ideal gas? (2 points)
Real gases differ most from an ideal gas at low temperatures and high pressures.
For the following reaction, identify the oxidized element, the reduced element, the oxidizing agent, and the reducing agent. You will not use all of the terms given. 2Na(s) + S(s) -->Na2S(s) Oxidizing agent
S
For the following reaction, identify the oxidized element, the reduced element, the oxidizing agent, and the reducing agent. You will not use all of the terms given. 2Na(s) + S(s) -->Na2S(s) Reduced
S
What is the temperature of absolute zero in Kelvin? What is it on the Celsius scale? (2 points)
The temperature of absolute zero in Kelvin is 0 K or -273.15℃ on the Celsius scale.
What is theoretical yield? (2 points)
The theoretical yield is the maximum amount of product that could be formed from given amounts of reactants.
Describe the motion of the particles in a gas.
The three characteristics that describe the motion of the particles in a gas are rapid, constant and random causing them to collide with one another and the walls of their container, the particles travel in a straight-line paths between collisions and a gas fills all the available space in its container.
What three characteristics describe the motion of the particles in a gas? (3 points)
The three characteristics that describe the motion of the particles in a gas are rapid, constant and random causing them to collide with one another and the walls of their container, the particles travel in a straight-line paths between collisions and a gas fills all the available space in its container.
What are the three factors that affect gas pressure? (3 points)
The three factors that affect gas pressure are the amount of gas, the volume, and the temperature.
What are three factors that influence how fast a substance dissolves?
The three factors that influence how fast a substance dissolves are temperature, agitation and surface area.
What are three factors that influence how fast a substance dissolves? (3 points)
The three factors that influence how fast a substance dissolves are temperature, agitation and surface area.
List the three forms of carbon. (3 points)
The three forms of carbon are: 1) diamond 2) graphite 3) fullerenes.
Describe the general properties of solids.
The two general properties of solids are the orderly arrangement of their particles and the fixed locations of their particles.
What are the two general properties of solids? (2 points)
The two general properties of solids are the orderly arrangement of their particles and the fixed locations of their particles.
What two states of matter are known as condensed states? (2 points)
The two states of matter known as condensed states are liquids and solids.
What determines the type of decay a radioisotope undergoes? (3 points)
The type of decay a radioisotope undergoes is determined by the neutron-to-proton ratio in a radioisotope.
What is the value of STP (standard temperature and pressure)? (2 points)
The value of STP (standard temperature and pressure) is defined as 0℃ and a pressure of 101.3 kPa, or 1 atm.
What are the two classes of chemical reactions? (2 points)
Two classes of chemical reactions are oxidation-reduction (redox) reactions, in which electrons are transferred from one reacting species to another and all other reactions in which no electron transfer occurs.
What are the two different methods for balancing redox reactions? (2 points)
Two different methods for balancing redox reactions are the oxidation-number change method and the half-reaction method.
When are two liquids miscible? Give an example. (3 points)
Two liquids are miscible if they dissolve in each in all proportions.
Name two liquids that are immiscible? (2 points)
Two liquids that are immiscible are oil and water.
What are two possible arrangements of carbon atoms in an alkane? (2 points)
Two possible arrangements of carbon atoms in an alkane are in a straight chain or in a chain that has branches.
List two types of reactions that are not redox reactions. (2 points)
Two types of reactions that are not redox reactions are double replacement reactions and acid-base reactions.
List two types of redox reactions. (2 points)
Two types of redox reactions are single-replacement reactions and combination reactions.
What are two ways in which transmutation can occur? (2 points)
Two ways in which transmutation can occur are by radioactive decay or when particles bombard the nucleus of an atom.
If a sample of gas occupies 6.80 L at 325°C, what will its volume be at 25°C if the pressure does not change? Show your work.
Use Charles's Law (all temps have to be in Kelvin K where 0C = 273K so you just add 273 to whatever the C is to get the K) which states the Initial Volume / Initial Temperature = New Volume / New Temperature so our initial Volume V1 = 6.80L and our T1 (in K) = 325 + 273 = 598K and we know our new T2 = 25 + 273 = 298 K. So 6.80L/598K = V2/298K. To solve for V2 we multiply both sides by 298K and cancel out the K's. which means V2 = 6.80L X 298/598 = 3.39L (rounded to three significant digits)
2-methlypentane
Use the rules for naming branched-chain alkanes on page 717 in the textbook to name the compounds in questions 4 and 5. (4 points, 2 points each)
3-ethyl-heptane
Use the rules for naming branched-chain alkanes on page 717 in the textbook to name the compounds in questions 4 and 5. (4 points, 2 points each)
How many liters of solution will be produced when diluting 1.65 L of a 0.432 M KI solution to 0.212 M KI? Show your work.
V2 = M1 x V1/M2 V2 = 0.432 M KI x 1.65L / 0.212 M KI V2 = 3.36 L
Define cracking. (2 points)
What characteristics are used to classify coal? (2 points)
When a container of gas is heated, what happens to the pressure of the gas? Why? (3 points)
When a container of gas is heated, the pressure of the gas also increases.
In general, what do acids and bases produce when they react?
When mixed, acids and bases neutralize one another and produce salts, substances with a salty taste and none of the characteristic properties of either acids or bases.
When you dilute a solution, what happens to the number of moles per unit volume? What happens to the total number of moles of solute? (4 points)
When you dilute a solution, the number of moles per unit volume decreases but the total number of moles of solute does not change.
When you open a can of a carbonated drink, how does the gas react? (3 points)
When you open a can of a carbonated drink, the gas reacts by the carbon dioxide gas coming out of the soda since the liquid cannot hold as much of the gas without the pressure remaining as tight as when the can was closed. The carbon dioxide bubbles out of the soda into the air until the soda goes flat with no more carbonation.
Identify the type of reaction: 2NaN3-->2Na + 3N2.
decomposition reaction
As a substance cools, its kinetic energy _____.
decreases
The boiling point of a liquid _____ as the atmospheric pressure decreases.
decreases
A(n) _____ will remove sufficient water from the air to dissolve completely and form solutions. Sodium hydroxide is an example.
deliquescent
A(n) _____ is a substance used to absorb moisture from the air and create a dry atmosphere.
desiccant
The Kelvin temperature of a substance is _____ proportional to the average kinetic energy to the particles of the substance.
directly
The average kinetic energy of the particles in a substance is _____ proportional to the substance's temperature.
directly
Solute
dissolved particles in a solution
According to the Bronsted-Lowry theory, acids _____.
donate hydrogen ions
Identify the type of reaction for the following. 2NaCN(aq) + H2SO4(aq) → 2HCN(g) + Na2SO4(aq)
double-replacement reaction
give an example for each of these colloid systems. Solid-liquid
egg white, jelly, paint, blood, starch in water and gelatin
All collisions between particles in a gas are perfectly _____.
elastic
A(n) _____ is a colloidal dispersion of a liquid in a liquid.
emulsion
Heat
energy that transfers from one object to another because of a temperature difference between the objects (thermal energy)
The _____ of a system is the heat content of the system at constant pressure.
enthalpy
_____ is used to account for the heat transfer between the system and its surroundings.
enthalpy
A conversion that occurs at the surface of a liquid that occurs even when the liquid is not boiling is called _____.
evaporation
Surroundings
everything else beyond the system
The particles in a(n) _____ are considered to be small, hard spheres with an insignificant volume that are spread relatively far apart.
gas
The _____ results from the force exerted by a gas per unit surface area of an object.
gas pressure
Cis-trans isomers
geometric isomers have atoms joined in the same order, but the spatial orientation of the groups differs
A(n) _____ is a transparent fusion product of inorganic substances that have cooled to a rigid state without crystallizing.
glass
What distinguishes a colloid from a solution and a suspension?
have particles larger than those in solutions and smaller than those in suspensions
The value of ΔH of a reaction can be determined by measuring the _____ of the reaction at constant pressure.
heat transfer
The difference between ammonia's low boiling point (-33°C) and water's high boiling point (100°C) is due to _____.
hydrogen bonding
Water molecules are held to one another by _____.
hydrogen bonding
Ionic compounds that cannot be solvated to any significant extent are considered nearly _____.
insoluble
All _____ are electrolytes because they dissociate into ions.
ionic compounds
Acids and bases are classified as strong or weak based on the degree to which they _____.
ionize in water
Calculate the pH of each solution in questions 8-11. (8 points, 2 points each) [H+] = 0.045 M
ph = -log(0.045) ph = 1.35
Calculate the pH [H+] = 8.7 × 10-6 M
ph = -log(8.7 x 10-6) ph = 5.1
Use the hydrogen-ion concentrations to calculate the pH of each solution in questions 12-13. (4 points, 2 points each) [H+] = 1.0 × 10-12 M
ph = 12
Calculate the pH [H+] = 1.2 × 10-3 M
ph = 2.9
Use the hydrogen-ion concentrations to calculate the pH of each solution in questions 12-13. (4 points, 2 points each) [H+] = 1 × 10-4 M
ph = 4
As a rule, _____ solvents like water can dissolve ionic compounds and polar compounds.
polar
The sign of ΔH is _____ for an endothermic reaction.
positive
the balanced equation gives us a ratio of reactants and products. Use the balanced equation provided N2(g) + 3H2(g) --> 2NH3(g), Number of atoms H2
2
the balanced equation gives us a ratio of reactants and products. Use the balanced equation provided N2(g) + 3H2(g) --> 2NH3(g), Number of atoms N2
2
Use coefficients to balance the following chemical equations. hydrogen peroxide → water + oxygen
2 H2O2 --> 2 H2O + O2
The substance that loses electrons is the _____ agent.
reducing
Identify the oxidized substance, the reduced substance, the oxidizing agent, and the reducing agent for the following: 2Na + S-->Na2S.
reducing agent = oxidized = Na and oxidizing agent = reduced = S
Identify each of the following processes as either oxidation or reduction Br2 + 2e- 2Br-
reduction
Identify each of the following processes as either oxidation or reduction Zn2+ + 2e- Zn
reduction
The temperature of the boiling liquid never _____ its boiling point.
rises above
Which of the following heating techniques produces a smooth glass bend?
rotating the tubing in the flame so that the tube is heated uniformly
A crystal has _____.
sides
trans configuration
similar groups are on opposite sides of a double bond
Cis configuration
similar groups are on the same side of a double bond
Identify the type of reaction for the following. Zn(s) + Cu(NO3)2(aq) → Cu(s) + Zn(NO3)2(aq)
single-replacement reaction
Another characteristic of bases is that they feel _____.
slippery
A solution of KCl contains 34.75 g of solute in 250 mL of solution. Determine the molarity of the solution. Show your work.
solution concentration = 34.75 g KCl/250mL molar mass of KCl = 74.5513 g/mol 34.75g KCl/250mL x 1 mol KCl/74.5513 g/mol x 1000mL/1L = 1.86M
A _____ dissociates completely into metal ions and hydroxide ions in an aqueous solution.
strong base
An atom or group of atoms that can take the place of a hydrogen atom on a parent hydrocarbon molecule is called a _____.
substituent
A(n) _____ is any substance that interferes with the hydrogen bonding between water molecules and reducing surface tension.
surfactant
The boiling point of a liquid is the _____ at which the vapor pressure of the liquid is just equal to the external pressure on the liquid.
temperature
Specific heat
the amount of heat it takes to raise the temperature of 1 g of a substance 1°C
Heat capacity
the amount of heat that is needed to increase the temperature of an object exactly 1°C
Potential energy
the energy a substance has because of its composition
Chemical energy
the energy stored in the chemical bonds of a substance
Define molar heat of solidification.
the heat lost when one mole of a liquid substance solidifies at a constant temperature.
What does the term radioactivity refer to?
the spontaneous emission of rays or particles from certain elements, such as uranium.
Endothermic process
the system gains heat as the surroundings lose heat
Exothermic process
the system releases heat to its surroundings
An empty space with no particles and no pressure is a(n) _____.
vacuum
The _____ is the measure of the force exerted by a gas above a liquid.
vapor pressure
The _____ is the result of molecules escaping from the surface of the liquid and entering the vapor stage.
vapor pressure
Water contained in a crystal is _____.
water of hydration
Define dissolution.
when a substance placed in contact with a solvent becomes incorporated into the solvent
Dissolution
when a substance placed in contact with a solvent becomes incorporated into the solvent
give an example for each of these colloid systems. Gas-liquid
whipped cream
The SI unit of pressure is the _____.
pascal (Pa)
Calculate the pH [H+] = .0015 M
ph = -log (.0015) ph = 2.824
Weak electrolyte
conducts an electric current poorly because only a fraction of the solute exists as ions
A 2.78 L air sample has a pressure of 145 kPa at 15°C. What temperature (Celsius) would this sample be if it expanded to 3.45 L under a pressure of 241 kPa? Show your work. (4 points)
(1) P1 = 145kPa V1 = 2.78L T1 = 15C + 273 = 288K P2 = 241kPa V2 = 3.45L (2) T2 = X (3) P1V1/T1 = P2V2/T2 so (4) T2 = P2V2T1/P1V1 (5) T2 = (241kPa)(3.45L)(288K)/(145kPa)(2.78L) = 594K - 273 = 321C
A gas sample has a pressure of 221 kPa at 66°C. What would the pressure be if the sample is heated up to 88°C? Show your work. (4 points)
(1) P1 = 221kPa T1 = 66C + 273 = 339K T2 = 88C + 273 = 361K (2) P2 = X (3) P1/T1 = P2/T2 so (4) P2 = P1T2/T1 (5) P2 = (221kPa)(361K)/(339K) = 235kPa
The formula for Boyle's Law is where is the initial pressure, is the initial volume, is the final pressure, and is the final volume. To solve these problems: (1) identify all that is known; (2) identify what is unknown; (3) write the equation; (4) isolate the unknown; and, (5) calculate the answer. HINT: Always pay attention to the units of measure. Use these as a way to check that you wrote your equation properly and that you solved for the correct item. Example: (1) P1 = 760 torr V1 = 20.0 liters P2 = 380 torr (2) V2 = X (3) P1V1 = P2V2 so (4) V2 = P1V1 / P2 (5) V2 = (760 torr)(20.0L)/(380 torr) = 40.0 L Torr/torr cancels out, leaving the final unit as L. The answer should be correct if the math is correct. Show your work in order to receive partial credit if you can set up and identify the correct equation. Always include the unit of measure, or you will lose a point. A gas with a volume of 2.5 L at a pressure of 260 kPa expands to a volume of 5.5 L. What is the pressure of the container if the temperature remains the same? Show your work. (4 points)
(1) P1 = 260kPa V1 = 2.5L V2 = 5.5L (2) P2 = X (3) P1V1=P2V2 so (4) P2 = P1V1/V2 (5) P2 = (260kPa)(2.5L)/(5.5L) = 118.18kPa = 120kPa
The formula for Gay-Lussac's Law is P1 / T1 = P2 / T2 or P1T2 = P2T1. Use the same steps in solving these problems as you have for Boyle's Law and Charles's Law. All temperatures must be in Kelvin before doing your calculations. The pressure in a container is 345 kPa at 305 K. The gas is heated until the pressure reaches 401 kPa. What is the final temperature of the gas? Show your work. (4 points)
(1) P1 = 345kPa T1 = 305K P2 = 401kPa (2) T2 = X (3) P1/T1 = P2/T2 so (4) T2 = P2T1/P1 (5) T2 = (401kPa)(305K)/(345kPa) = 355K
The volume of a gas at 26.0°C and 75.0 kPa is 10.5 L. The pressure is increased to 116 kPa. What final temperature would be required to reduce the volume to 9.50 L? Show your work. (4 points)
(1) P1 = 75.0kPa V1 = 10.5L T1 = 26.0C + 273 = 299K P2 = 116kPa V2 = 9.50L (2) T2 = X (3) P1V1/T1 = P2V2/T2 so (4) T2 = P2V2T1/P1V1 (5) T2 = (116kPa)((9.50L)(299K)/(75.0kPa)(10.5L) = 418K - 273 = 145C
The working ratio for Charles's Law is or . Writing the equation the second way works exactly like the Boyle's Law equation. Personal preference: use whichever one works for you. The five steps for solving Charles's Law problems are essentially the same as in Boyle's Law (refer to #2 above). HINT: Always convert temperature to Kelvin scale before making your calculations. Use the same scale that is used when presenting the problem. If the question uses Celsius, answer in Celsius; if the question uses Kelvin, answer in Kelvin. A gas sample occupies 3.2 L at 320 K. What will its volume be at 240 K? Show your work. (4 points)
(1) V1 = 3.2L T1 = 320K T2 = 240K (2) V2 = X (3) V1/T1 = V2/T2 so (4) V2 = V1T2/T1 (5) V2 = (3.2L)(240K)/320K = 2.4L
Write a condensed formula using (CH2-) for questions 6-8. (9 points, 3 points each) 2,2-dimethylbutane
(CH3)3-C-CH2-CH3
Concentrated solution
contains a large amount of solute
Dilute solution
contains a relatively small amount of solute
List the 3 steps in acid-base titration. (3 points)
1. A measured volume of an acid solution of unknown concentration is added to a flask. 2. Several drops of an indicator are added to the solution while the flask is gently swirled. 3. Measured volumes of base of known concentration are mixed into the acid until the indicator just barely changes color.
Write the 6 rules for assigning oxidation numbers. (6 points, 1 point/rule)
1. The oxidation number of a monatomic ion is equal in magnitude and sign to its ionic charge. 2. The oxidation number of hydrogen in a compound is +1, except in metal hydrides, such as NaH, where it is -1. 3. The oxidation number of oxygen in a compound is -2, except in peroxides, such as H2O2 where it is -1, and in compounds with the more electronegative fluorine, where it is positive +2. 4. The oxidation number of an atom in uncombined form is 0. 5. For any neutral compound, the sum of the oxidation numbers of the atoms in the compound must equal 0. 6. For a polyatomic ion, the sum of the oxidation numbers must equal the ionic charge of the the ion.
If you have one mole of any gas, how many liters do you have at STP?
22.4 L / 1 mol at STP for any gas
the balanced equation gives us a ratio of reactants and products. Use the balanced equation provided N2(g) + 3H2(g) --> 2NH3(g), Volume at STP N2
22.4L
How many moles of aluminum chloride are formed when 2.5 moles of chlorine gas react with aluminum? Write the balanced equation and calculate the number of moles. Show your work.
2Al + 3Cl2 --> 2AlCl3 ratio is 3 moles of Cl2 produces 2 moles of AlCl3 (3 mol Cl2/2 mol AlCl3) So I have 2.5 moles of Cl2 and I want to know how many moles of AlCl3 that'll produce for me if I have enough Al to interact with it so I multiply the 2.5 moles I have Cl2 times the ratio to tell me how many moles of AlCl3 that'll leave me with (I have to flip the ratio to get AlCl3 on top). 2.5 mol Cl2 X (2 mol AlCl3 / 3 mol of Cl2) = 5/3 mol AlCl3 or rounding in decimals 1.7mol of AlCl3
For the reaction of aluminum sulfate solution with ammonium hydroxide solution, Net ionic equation
2Al³⁺ + 6OH⁻ → 2Al(OH)3(s)
In sulfuric acid (aqueous solution), potassium iodide reacts according to the following equation. H2SO4(aq) + KI(s) K2SO4(aq) + I2(g) + SO2(g) + H2O(l) Use this information to answer questions 10-12. What is the reduction half-reaction? (3 points)
2H+ + SO42- + 2e- è SO2 + 2H2O
In sulfuric acid (aqueous solution), potassium iodide reacts according to the following equation. H2SO4(aq) + KI(s) K2SO4(aq) + I2(g) + SO2(g) + H2O(l) Use this information to answer questions 10-12. What is the balanced equation? (3 points)
2H2SO4(aq) + 2KI(s) --> K2SO4(aq) + I2(g) + SO2(g) + 2H2O(l)
the balanced equation gives us a ratio of reactants and products. Use the balanced equation provided N2(g) + 3H2(g) --> 2NH3(g), Number of atoms NH3
4
Table 11.2 on page 381 in the textbook shows the activity series of metals. Elements toward the top of the chart will displace metals below them in a compound. Li, K, Ca, and Na will replace H in an acid or in water. Mg through Pb will replace H in an acid only.In the following equations, complete and balance the reactions that take place. Write "no reaction" beside those that will not react. Fe(III) + Pb(SO4)2 →
4Fe + 3Pb(SO4)2 à 2Fe2(SO4)3 + 3Pb
Calculate [H+] for each solution in questions 14-15. Show your work. (6 points, 3 points each) pH = 5.00
5.00 = -log[H+] log[H+] = - 5.00 [H+] = 1.00 x 10-5
What is the molarity of a solution in which 58 g of NaCl are dissolved in 1.0 L of solution?
58 g NaCl x 1 mol NaCl/58.5 g NaCl = 0.99 moles 0.99 moles/1.0 L = 0.99M (Molarity M = number of moles divided by Volume)
Define a Lewis acid. (2 points)
A Lewis acid is a substance that can accept a pair of electrons to form a covalent bond.
Why does a carbon atom form four covalent bonds? (3 points)
A carbon atom forms four covalent bonds because carbon has four valence electrons.
What are the structural characteristics of alkenes? (3 points)
A carbon-carbon double bond is shown in structural formulas as two parallel lines. At least one carbon-carbon bond in an alkene is a double covalent bond. Other bonds may be single carbon-carbon bonds and carbon-hydrogen bonds.
What are the structural characteristics of alkynes? (3 points)
A carbon-carbon triple bond is shown in structural formulas as three parallel lines. At least one carbon-carbon bond in an alkyne is a triple covalent bond. Other bonds may be single or double carbon-carbon bonds and carbon-hydrogen bonds.
What is a chemical equation?
A chemical equation is a representation and products to write chemical equations; the formula of the reactants are connected by an arrow with the formula of the products.
What are coefficients?
A coefficient is a number placed in front of a chemical symbol or formula. It shows how many atoms or molecules of the substance are involved in the reaction.
For the following reaction, identify the oxidized element, the reduced element, the oxidizing agent, and the reducing agent. You will not use all of the terms given. 4Al(s) + 3O2(g) Al2O3(s) Oxidized
Al
For the reaction of aluminum sulfate solution with ammonium hydroxide solution, write a Balanced chemical equation
Al2(SO4)3(aq) + 6(NH4)OH(aq) → 2Al(OH)3(s) + 3(NH4)2SO4(aq)
List an advantage of using a pH meter for monitoring sewage, industrial wastes, and soil pH. (2 points)
An advantage of using a pH meter for monitoring sewage, industrial wastes, and soil pH is because the color and cloudiness of the solutions do not affect the accuracy of the pH value obtained.
What is an aliphatic compound? (2 points)
An aliphatic compound is any compound not classified as an aromatic compound.
What is an aromatic compound? (2 points)
An aromatic compound is an arene or defined as an organic compound that contains a benzene ring or other ring in which the bonding is like that of benzene.
Refer to Figure 20.15 on page 731 in the textbook. At what temperature does lubricating oil separate out? (2 points)
At >400 degrees Celsius lubricating oil separates out.
State Boyle's Law. (2 points)
At constant temperature, the volume of a given mass of dry gas is inversely proportional to its pressure.
You have one mole of sulfuric acid (H2SO4). Determine the number of molecules of sulfuric acid, the mass (in grams) of sulfuric acid, and how many atoms of each element are present.
Avogadro's number for the number of molecules per mole is 6.022x10^23 so since I have one mole I have 6.022x10^23 molecules. The mass in grams I would get by adding up the atomic mass for the number of each element I have which is H = 1.0079g x 2 = 2.0158g S = 32.065g O = 15.999g x 4 = 63.996g add it all up = 98.0678g H2SO4 there are 2 atoms of hydrogen, 1 atom of sulfur, and 4 atoms of oxygen.
Define radioactivity. (2 points)
Radioactivity is the spontaneous emission of rays or particles from certain elements, such as uranium.
Balance each redox equation by using the oxidation-number-change method in questions 6-7. (6 points, 3 points each) Ba(ClO3)2(s) BaCl2(s) + O2(g)
Ba(ClO3)2(s) --> BaCl2(s) + 3O2(g)
How is boiling a cooling process similar to evaporation?
Boiling can be considered as a cooling process because as a liquid reaches its critical temperature, heat escapes through rapid evaporation. ... hot vapors escape liquid and take energy with them during the boiling process. Because heat is leaving, this is actually a cooling process.
What is Brownian motion? (3 points)
Brownian motion is the chaotic movement of colloidal particles.
Define neutron moderation. (2 points)
Neutron moderation is a process that slows down neutrons so the reactor fuel can capture them to continue the chain reaction.
A piece of metal is heated and placed in a foam-cup calorimeter containing 100.0 mL of water at 28.1°C. The water reaches a maximum temperature of 30.3°C. How many joules of heat are released by the metal? Show your work. (4 points)
C (water) = 4.18 J / (g x °C) V = 100.0 mL T (I) = 28.1°C T (f) = 30.3°C density = 1.00 g / mL m = 100.0ml x 1.00g / mL = 100.0 g ΔT = T(f) = T(i) = 30.3°C - 28.1°C = 2.2°C ΔH = -q (surr) = -m x C x ΔT = -(100.0g)(4.18J/(g x °C))(2.2°C) = -920J
you have one mole of sugar, How many atoms of each element are present?
C is 6 X 6.02 × 10^23 = 3.61 × 10^24 atoms H is 12 x 6.02 x 10^23 = 7.22 x 10^24 atoms O is 6 X 6.02 × 10^23 = 3.61 × 10^24 atoms
1. Complete gain of electrons (ionic reactions) 2. Shift of electrons away from an atom in a covalent bond 3. Loss of oxygen 4. Loss of hydrogen by a covalent compound 5. Decrease in oxidation number
Complete the Processes Leading to Oxidation and Reduction Chart below. Number your answers in the same order as shown in the table below (1-5). (10 points, 2 points each)
What is compressibility?
Compressibility is a measure of how much the volume of matter decreases under pressure Compressibility is a measure of how much the volume of matter decreases under pressure.
Oxidation is now defined to mean _____.
complete or partial loss of electrons or gain of oxygen
Write a condensed formula using (CH2-) for questions 6-8. (9 points, 3 points each) 3-ethylhexane
CH3-CH2 -CH-CH2-CH2-CH3 | CH2-CH3
Write a condensed formula using (CH2-) for questions 6-8. (9 points, 3 points each) Octane
CH3-CH2-CH2- CH2- CH2- CH2- CH2- CH3
Use coefficients to balance the following chemical equations. methane + oxygen → carbon dioxide + water
CH4 + 2 O2 --> CO2 + 2 H2O
Write the skeleton equation for the following questions. methane + oxygen → carbon dioxide + water
CH4 + O2 --> CO2 + H2O
Table 11.2 on page 381 in the textbook shows the activity series of metals. Elements toward the top of the chart will displace metals below them in a compound. Li, K, Ca, and Na will replace H in an acid or in water. Mg through Pb will replace H in an acid only.In the following equations, complete and balance the reactions that take place. Write "no reaction" beside those that will not react. Ca + HOH -->
Ca + 2HOH àCa(OH)2 + H2
Determine the oxidation number of chlorine for each of the substances and list the rules that apply in questions 8-11. (8 points, 2 points each) Ca(ClO4)2
Ca = +2 O = -2 Cl = +7 Rules 1, 3, and 5.
Table 11.2 on page 381 in the textbook shows the activity series of metals. Elements toward the top of the chart will displace metals below them in a compound. Li, K, Ca, and Na will replace H in an acid or in water. Mg through Pb will replace H in an acid only.In the following equations, complete and balance the reactions that take place. Write "no reaction" beside those that will not react. Cu + AgNO3 →
CuNO3 + Ag
Define cyclic hydrocarbon. (2 points)
Cyclic hydrocarbon is a compound that contains a hydrocarbon ring.
State Dalton's law of partial pressure.
Dalton's law of partial pressure states that, at constant volume and temperature, the total pressure exerted by a mixture of gases is equal to the sum of the partial pressures of the component gases.
All leftover or waste chemicals can be flushed down the drain with large amounts of water.
False
If you have not handled any chemicals, you do not need to wash your hands at the end of the experiment.
False
If your clothing catches on fire, you should run immediately to the safety shower.
False
To save materials, it is a good idea to return surplus chemicals to their appropriate, labeled reagent bottles.
False
True or false? All substances are more soluble at higher temperatures. (1 point)
False
When does fission occur? (3 points)
Fission occurs when the nuclei of certain isotopes are bombarded with neutrons and then the nuclei split into smaller fragments.
How do fission reactions and fusion reactions compare? (3 points)
Fission reactions compare to fusion reactions because fusion reactions, in which small nuclei combine, release much more energy than fission reactions, in which large nuclei split apart and form smaller nuclei. Fusion reactions occur only at very high temperatures
For aqueous solutions, what does the product of the hydrogen ion concentration and the hydroxide ion concentration equal? Hint: Memorize this value for the final exam. (2 points)
For aqueous solutions, the product of the hydrogen ion concentration and the hydroxide ion concentration equlas 1 X 10-14.
What is the effect of temperature on the solubility of gases in liquid solvents compared to that of solids?
For many solids dissolved in liquid water, the solubility increases with temperature. The increase in kinetic energy that comes with higher temperatures allows the solvent molecules to more effectively break apart the solute molecules that are held together by intermolecular attractions.
List four practical uses of radioisotopes. (4 points)
Four practical uses of radioisotopes include analyzing the matter, studying plant growth, diagnosing medical problems, and treating diseases.
Define freezing-point depression. (2 points)
Freezing-point depression is the difference in temperature between the freezing point of a solution and the freezing point of the pure solvent.
What allows particles in both gases and liquids to take the shape of their containers? (2 points)
Gases and liquids can take the shape of their container because the particles have enough space to move around each other.
How did Gilbert Lewis define an acid and a base? (3 points)
Gilbert Lewis said an acid accepts a pair of electrons whereas a base donates a pair of electrons during a reaction.
State Graham's law of effusion.
Graham's law of effusion states that the rate of effusion of a gas is inversely proportional to the square root of the gas's molar mass.
Which of the following is not a correct technique for heating a liquid in a test tube while using a gas burner?
Heat only the bottom of the tube.
What are heats of reaction reported as? (2 points)
Heats of reaction are reported as ΔH, which is equal to the heat transfer at constant pressure.
Hydrogen and chlorine gases combine to form hydrogen chloride gas. Write the equation. What is the limiting reagent when 18.0 g of H2 react with 40.0 g of Cl2? (5 points)
H₂ + Cl₂ → 2HCl 18.0g H₂ X 1 mol H₂ / 2.0g H₂ X 1 mol Cl₂ / 1 mol H₂ X 70.9g Cl₂ / 1 mol Cl₂ = 638.1g Cl₂ Therefore, Cl₂ is our limiting reagent.
Sulfuric acid may be neutralized using sodium hydroxide. (This generates a tremendous amount of heat, so don't try it at home.) How many grams of sodium hydroxide would be needed to neutralize 200.0 g sulfuric acid?
H₂SO₄ + 2NaOH → Na₂SO₄ + 2H₂O 200.0g H₂SO₄ X 1 mol H₂SO₄ / 98.079g H₂SO₄ X 2 mol NaOH / 1 mol H₂SO₄ X39.997g NaOH / 1 mol NaOH = 163.1g NaOH
identify the reactants and the products. iron + oxygen → iron (III) oxide
Iron and Oxygen are the reactants and Iron (III) oxide is the product
Define isomers. (2 points)
Isomers are compounds that have the same molecular formula but different molecular structures.
What are isomers?
Isomers are compounds that have the same molecular formula but different molecular structures.
In a 0.2000 M solution of a monoprotic weak acid, [H+] = 9.86 × 10-4 M. What is the Ka for this acid? Show your work. Remember, a strong base dissociates completely into metal ions and hydroxide ions in an aqueous solution. A weak base reacts with water to form the conjugate acid of the base and hydroxide ions.
Ka = 9.86 x 10-4 x 9.86 x 10-4 / (0.2000 - 9.86 x 10-4) = 4.89 x 10-6
Write the base dissociation constant (Kb) equation. (3 points)
Kb = [conguate acids] x [OH-] / [base]
How many kilojoules of heat must be removed to freeze a container of water at 0°C if the water has a mass of 1.50 × 102 g?
Knowns: Initial and final temperatures are 0°C ΔHsolid = -6.01 kJ/mol mwater = 1.5 x 102 g Unknow: ΔH = ? kJ ΔH = 1.5 x 102 g H2O(l) x -6.01kJ / 1 mol H2O(l) x 1 mol H2O(l) / 18.0g H2O(l) = -50.1 kJ
The Ideal Gas Law adds one item to the three we have been working with, n = number of moles of the gas. Therefore, the new equation is PV = nRT. R is a constant we can calculate. Since a mole of a gas occupies 22.4 L at STP, we will use these values. R = PV / Tn = (101.3 kPa)(22.4 L) / (273 K)(1 mol) = . We call this number the ideal gas constant. With this information, you can calculate the volume, pressure, number of moles, or temperature of an ideal gas. What is the pressure inside a 3.00 L ball that contains 1.23 mol of air at 32°C? Show your work. (4 points)
Knowns: V = 3.00 L T = 32 °C R = 8.31 (L * kPa) / (K * mol) n = 1.23 mol of air Unknown: P = ? kPa Calculate: T = 32°C + 273 = 305 K Ideal Gas Law: P x V = n x R x T P = (n x R x T) / V P = [ 1.23 mol of air x 8.31 (L * kPa) / (K * mol) x 305 K] / 3.00 L P = 1039.1655 kPa P = 1040 kPa
If the hydroxide-ion concentration of an aqueous solution is 1 × 10-3 M, what is the [H+] in the solution? Is the solution acidic, basic, or neutral? Show your work. (3 points)
Knowns: [OH-] = 1 x 10-3M Kw = 1 x 10-14 1 x 10-14 = 1 x 10-3 x [H+] [H+] = 1 x 10-11 basic
Water is decomposed to yield hydrogen gas and oxygen gas in an endothermic reaction. How many kilojoules of heat are required to decompose 114 mol H2O? 2H2O(l) + 571.6 kJ 2H2(g) + O2(g)
Knowns: amount of H2O(l) that decomposes = 114 mol ΔH = 571.6 kJ for 2 mol H2O Unknown: ΔH = ?kJ for 114 mol H2O 571.6kJ/2 mol H2O ΔH = 114 mol H2O(l) x 571.6kJ/2mol H2O(l) = 32,581.2kJ = 32,600kJ
Calculate the amount of heat (in kJ) released when 1.52 mol of hydrogen peroxide decomposes. Show your work. (4 points) 2H2O2(l) 2H2O(l) + O2(g) + 196.4kJ
Knowns: amount of H2O2(l) that decomposes = 1.52 mol ΔH = 196.4kJ ΔH = 1.52 mol H2O2(l) x 196.4kJ/2 mol H2O2(l) = 149.264kJ = 149kJ
How much heat in kJ is released when 0.677 mol NaOH(soln) is dissolved in water? (ΔH(soln) = -44.5 kJ/mol for NaOH) NaOH(s) Na+(aq) + OH-(aq) + 44.5 kJ/mol
Knowns: ΔH(soln) = 44.5 kJ/mol amount of NaOH(s) dissolved = 0.677 mol Unknown: ΔH = ? kJ ΔH = 0.677 mol NaOH(s) x -44.5 kJ / 1 mol NaOH(s) = -30.1 kJ
Calculate the ΔH° for the reaction: Br2(g) Br2(l). Show your work. (4 points)
Knowns: ΔHf°Br2(g) = 30.91 kJ/mol ΔHf°Br2(l) = 0.0 kJ/mol Unknown: ΔH° = ? kJ Br2(g) --> Br2(l) ΔH° = 0.0 kJ/mol - 30.91 kJ/mol = -30.91 kJ/mol
Ethanol is mixed with gasoline to make gasohol. What is the percent by volume of ethanol in gasohol when 95 ml of ethanol is added to sufficient gasoline to make 1.0 L of gasohol? Show your work. (3 points)
Knowns: volume of solute = 95mL ethanol, volume of solution = 1.0L = 1000mL Unknown: Percent by volume = ? % ethanol (v/v) Percent by volume (% (v/v)) = volume of solute / volume of solution x 100% %(v/v) = 95mL ethanol/1000mL x 100% = 9.5%
Table 11.2 on page 381 in the textbook shows the activity series of metals. Elements toward the top of the chart will displace metals below them in a compound. Li, K, Ca, and Na will replace H in an acid or in water. Mg through Pb will replace H in an acid only.In the following equations, complete and balance the reactions that take place. Write "no reaction" beside those that will not react. Li + NaCl →
LiCl + Na
In the equation: moles of solute = M1 × V1 = M2 × V2, M1 and V1 are conditions of the initial solution and M2 and V2 are the conditions in the final volume. Use this information to solve the problems in questions 9 and 10. (3 points each) What is the molarity of a NaCl solution that becomes 0.15 M NaCl when 2.0 L is diluted to 6.5 L? Show your work.
M1 x V1 = M2 x V2 M1 = (M2 x V2)/V1 M1 =(0.15M NaCl x 6.5L)/2.0L = 0.49M NaCl
Use the information from Table 11:1 on page 368 in the textbook to write a word equation that includes all the information in this equation. Include number of particles, state of matter, etc.Mg(s) + 2AgNO3(aq) → 2Ag(s) + Mg(NO3)2(aq)
Magnesium + Silver Nitrate --> Silver + Magnesium Nitrate
Name the two metals that are sacrificial metals for iron objects. (2 points)
Magnesium and zinc are sacrificial metals for iron objects.
When preparing to light a gas burner, which of the following do you do first?
Make sure that flammable chemicals are not being used.
Write the formula for molality. (2 points)
Molality (m) = moles of solute / kilogram of solvent
Define molar heat of solidification. (2 points)
Molar heat of solidification is the heat lost when one mole of a liquid substance solidifies at a constant temperature.
Define molar heat of vaporization. (2 points)
Molar heat of vaporization is the amount of heat required to vaporize one mole of a given liquid at a constant temperature.
How many moles of NaCl are in 5.4 L of 1.25 M NaCl? Show your work.
Moles of solute = molarity (M) x liters of solution (V) = 1.25 mol NaCl/1L x 5.4L = 6.8 mol NaCl
For the following reaction, identify the oxidized element, the reduced element, the oxidizing agent, and the reducing agent. You will not use all of the terms given. 2Na(s) + S(s) -->Na2S(s) Reducing agent
Na
Boiling is a _____ process, allowing particles with higher kinetic energy to escape.
cooling
Table 11.2 on page 381 in the textbook shows the activity series of metals. Elements toward the top of the chart will displace metals below them in a compound. Li, K, Ca, and Na will replace H in an acid or in water. Mg through Pb will replace H in an acid only.In the following equations, complete and balance the reactions that take place. Write "no reaction" beside those that will not react. Al + HOH →
No reaction
How do nuclear reactions differ from chemical reactions? (3 points)
Nuclear reactions differ from chemical reactions because unlike chemical reactions, nuclear reactions are not affected by changes in temperature, pressure, or the presence of catalysts. Also, nuclear reactions of a given radioisotope cannot be slowed down, sped up, or stopped.
For the following reaction, identify the oxidized element, the reduced element, the oxidizing agent, and the reducing agent. You will not use all of the terms given. 4Al(s) + 3O2(g) Al2O3(s) Reduced
O2
Identify which atoms are oxidized and which are reduced, then identify the oxidizing agent and the reducing agent for each reaction in questions 15-16. Label your answers clearly. (8 points, 4 points each) PbO2(aq) + 4HI(aq) I2(aq) + PbI2(s) + 2H2O(l) Oxidized = Reduced = Oxidizing agent = Reducing agent =
Oxidized = I2 Reduced = Pb Oxidizing Agent = PbO2 Reducing Agent = Reducing agent is the iodine
How do particles in a liquid give liquids a definite volume? (2 points)
Particles in liquids give liquid a definite volume because the particles are still in close contact with each other so they can't separate and change the volume.
What is percent by mass? (2 points)
Percent by mass of a solution is the ratio of the mass of the solute to the mass of the solution.
Which of the following is an appropriate procedure to be used when cutting and polishing a piece of glass tubing?
Place your thumbs behind the scratch and snap the glass.
Name the two noble metals. (2 points)
Platinum (Pt) and Gold (Au)
What process is used to separate the other gases from methane in natural gas? (2 points)
Propane and butane are separated from the other gases in natural gas by liquefaction.
Use the sample problem on page 550 in the textbook to answer questions 14 and 15. (4 points each) The solubility of a gas in water is 0.25 g/L at 120 kPa. What is the solubility if the pressure is increased to 250 kPa and the temperature is constant? Show your work.
S1/P1 = S2/P2 S1 = 0.26 g/L P1 = 120 kPa P2 = 250 kPa (0.26 g/L)/(120 kPa) = S2 / (250 kPa) S2 = (0.26 g/L)(250 kPa)/(120 kPa) S2 =0.54 g/L
What is the molarity of a 0.75 L solution that contains 9.2 g of NaCl? Show your work.
Solution concentration = 9.2g NaCl / 0.75L molar mas of NaCl = 58.5 g/mol 9.2g NaCl/0.75L x 1 mol NaCl/58.5 g NaCl = 0.21mol/L = 0.21M
Define standard heat of formation. (2 points)
Standard heat of formation of a compound is the change in enthalpy that accompanies the formation of one mole of a compound from its elements with all substances in their standard states.
Define standard heat of reaction. (2 points)
Standard heat of reaction is the difference between the standard heats of formation of all the reactants and products.
Define standard solution. (2 points)
Standard solution is the solution of known concentration.
Define sublimation.
Sublimation is the process of a physical change of a substance directly from a solid to a vapor, skipping the liquid phase.
When does sublimation occur in solids? (2 points)
Sublimation occurs in solids with vapor pressures that exceed atmospheric pressure.
Why does sugar dissolve faster when stirred into water rather than just adding the sugar into the water and letting it sit? (3 points)
Sugar dissolves faster when stirred into water rather than just adding the sugar into the water and letting it sit because fresh solvent, water, is continually brought into contact with the surface of the sugar.
The Combined Gas Law This law combines Boyle's Law, Charles's Law, and Gay-Lussac's Law. The Combined Gas Law is written as P1V1/T1 = P2V2/T2 or P1V1T2 = P2V2T1. For the final exam, know the three laws. However, this equation will allow you to solve any of the problems. Leave out any pair that does not have a given value. State the Combined Gas Law. (2 points)
The Combined Gas Law is the law that describes the relationship among the pressure, temperature, and volume of an enclosed gas.
Describe the Tyndall effect. (2 points)
The Tyndall effect is the scattering of visible light by colloidal particles.
How much of a radioactive sample remains after each half-life? (3 points)
The amount of each radioactive sample that remains after each half-life is half of the remaining radioactive atoms and the other half have decayed into atoms of a new element.
What is actual yield? (2 points)
The amount of product that actually forms when the reaction is carried out in the laboratory is called the actual yield.
Why is boiling-point elevation a colligative property? (2 points)
The boiling-point elevation is a colligative property because it depends on the concentration of particles and not on their identity.
What does the complete reaction of a strong base and a strong acid produce? What is this type of reaction called? (2 points)
The complete reaction of a strong acid and a strong base produces a neutral solution. This type of reaction is called a neutralization reaction.
What does a phase diagram indicate and how is it represented? (4 points) Hint: Be able to use a phase diagram like the one on page 462 to interpret information in questions on the final, such as boiling point, melting point, triple point, solid, liquid, gas, etc.
The conditions of pressure and temperature at which two phases exist in equilibrium are indicated on a phase diagram by a line separating the two regions representing the phases.
What is the end point? (2 points)
The end point is the point at which the indicator changes color.
A piece of metal is heated and placed in a foam-cup calorimeter containing 100.0 ml of water at 28.1°C. The water reaches a maximum temperature of 30.3°C. How many joules of heat are released by the metal? Show your work. (3 points) Use the word "Delta" to represent the Δ symbol where needed.
The energy in the form of heat gained by the water is equal to the energy lost by the metal so we need to figure out the joules of heat that equate to the 2.2 degree Celsius temperature rise. g = mL when dealing with water as this has to be solved with mass so energy gained of water = energy lost of metal = mass of water x temperature change of the water x constant calories energy = 4.186 kJ so Q=mC∆T (that's the official formula) and remember the triangle or Delta just means "change" m = mass in kg, c = 4.184J/kgxC and Delta T = temp change so for us Q = 0.1kg (because 100grams = 0.1kg since you divide by 1000) x 4.148kJ/kg/C x 2.2C cancel out all like terms and do the math and you get: 0.920kJ or multiply by 1000 for Joules since that's what it asked for so 920J
What factors influence the solubility of a substance? (2 points)
The factors that influence the solubility of a substance are temperature and pressure.
What is the first step in the refining of petroleum? (2 points)
The first step in the refining of petroleum is the distillation of crude oil into fractions according to boiling point.
List the five steps for the oxidation-number-change method. (5 points, 1 point/step)
The five steps for the oxidation-number-change method are: 1) Assign oxidation numbers to all the atoms in the equation. 2) Identify which atoms are oxidized and which are reduced. 3) Use on bracketing line to connect the atoms that undergo oxidation and another such line to connect those that undergo reduction. 4) Make the total increase in oxidation number equal to the total decrease in oxidation number by using appropriate coefficients. 5) Finally, make sure the equation is balanced for both atoms and charge.
What are the percentages of the different gases in natural gas?
The gases that compose natural gas are 80% methane, 10% ethane, 4% propane, 2% butane with the remaining 4% consisting of nitrogen and hydrocarbons of higher molar mass plus a small amount of the noble gas helium.
What gases compose natural gas and what are their respective percentages? (5 points)
The gases that compose natural gas are 80% methane, 10% ethane, 4% propane, 2% butane with the remaining 4% consisting of nitrogen and hydrocarbons of higher molar mass plus a small amount of the noble gas helium.
State the general rule for assigning oxidation numbers. (3 points)
The general rule for assigning oxidation numbers is a bonded atom's oxidation number is the charge that it would have if the electrons in the bond were assigned to the atom of the more electronegative element.
Which group of elements reacts violently with water to produce a hydroxide and hydrogen gas in an aqueous solution? (1 point)
The group of elements that reacts violently with water to produce a hydroxide and hydrogen gas in an aqueous solution is Group 1A.
On what does the heat capacity of an object depend? (2 points)
The heat capacity of an object depends on both its mass and its chemical composition.
Define heat of reaction. (2 points)
The heat of reaction is the enthalpy change for the chemical equation exactly as it is written.
Conjugate base
The ion or molecule that remains after an acid loses a hydrogen ion.
How does the kinetic energy of the liquid in hot water cause the sugar to dissolve faster than in cold water? (3 points)
The kinetic energy of the liquid in hot water causes the sugar to dissolve faster than in cold water because the water molecules are moving faster causing more collisions between the water and sugar.
What is a limiting agent in a chemical reaction? (2 points)
The limiting agent is the reactant that determines the amount of product that can be formed by a reaction.
What are the major attractions among alkanes, alkenes, and alkynes? (2 points)
The major attractions among alkanes, alkenes, and alkynes are weak van der Waals forces.
What is the mole fraction of a solute in solution? (2 points)
The mole fraction of a solute in a solution is the ratio of the moles of that solution to the total number of moles of solvent and solute.
What is the most accurate description of bonding in benzene? (3 points)
The most accurate description of bonding in benzene is the bonding electrons between carbon atoms are shared evenly around the ring.
In a(n) _____, the particles are arranged in an orderly, repeating, three-dimensional pattern.
crystal
Which nonvolatile solute would most likely lower the vapor pressure more, an ionic or a molecular solute? Why? (3 points)
The nonvolatile solute which would most likely lower the vapor pressure more between an ionic or a molecular solute is ionic because the decrease in a solution's vapor pressure is proportional to the number of particles the solute makes in a solution. The molecular solute's molecules do not dissociate as the ionic ones do.
At what pressure is the normal boiling point defined at the boiling point of a liquid? (2 points)
The normal boiling point is at 760mm.
Which one of the 4 H in ethanoic (acetic) acid can be released in an aqueous solution? (2 points)
The one of the 4 H in ethanoic acid that can be released in an aqueous solution is the hydrogen bonded to the highly electronegative oxygen.
Determine the oxidation number of chlorine for each of the substances and list the rules that apply in questions 8-11. (8 points, 2 points each) KClO3
The oxidation number for K is +1, Oxygen is -2 and Chloride is +5. Rules: 1, 3 and 5.
On page 462 in the textbook, you will find a phase diagram showing the temperatures and pressures where solids, liquids, and gases exist. What is the point at which all three meet known as? (2 points)
The point at which all three of solids, liquids and gases meet is known as the triple point.
How does the presence of a solute lower the freezing point of water? (3 points)
The presence of a solute lowers the freezing point of water because the shells of water of solvation disrupt the formation of the orderly pattern taken on in freezing. Therefore, more kinetic energy must be withdrawn from a solution than from the pure solvent to cause the solution to solidify.
How does the presence of salts and acids accelerate the corrosion of metals?
The presence of salts and acids accelerates corrosion by producing conductive solutions that make electron transfer easier. A positive or negative number assigned to an atom to indicate its degree of oxidation or reduction; the oxidation number of an uncombined element is zero.
How does an aerosol can work? (3 points)
The pressure of the gas inside a new can of spray paint is greater than the air pressure outside the can. When gas rushes though an opening in the top of the can, it propels, or forces, paint out of the can. As the can is used, the pressure decreases.
How do the properties of constitutional isomers differ? (3 points)
The properties of constitutional isomers differ in physical properties such as boiling point and melting point. They also have different chemical reactivities.
What properties of real gases cause them to differ from the Ideal Gas Law? (2 points)
The properties of real gases that cause them to differ from the Ideal Gas Law are they have volume and there are attractions between particles.
Define stoichiometry.
The quantitative relationship between substances in a chemical substance.
What is an excess reagent? (2 points)
The reactant that is not completely used up in a reaction is called the excess reagent.
What is the relationship between molar heat of fusion and molar heat of solidification? (3 points)
The relationship between molar heat of fusion and molar heat of solidification is that the quantity of heat absorbed by a melting solid is exactly the same as the quantity of heat released when the liquid solidifies so the molar heat of fusion = -molar heat of solidification.
Determine the oxidation number of each element and list the rules that apply in questions 4-7. (12 points, 3 points each) Na2O2
The rules that apply are 3 and 5. The oxidation number of oxygen is -1 (peroxide) and the oxidation number of sodium is +1.
Determine the oxidation number of each element and list the rules that apply in questions 4-7. (12 points, 3 points each) S2O3
The rules that apply are 3 and 5. The oxidation number of oxygen is -2 and the oxidation number of sulfur is +3.
Determine the oxidation number of each element and list the rules that apply in questions 4-7. (12 points, 3 points each) P2O5
The rules that apply are rules 3 and 5. The oxidation number of oxygen is -2 and the oxidation of phosphorous is +5.
List the seven steps of the half-reaction method. (7 points, 1 point/step)
The seven steps of the half-reaction method are: 1) Write the unbalanced equation in ionic form. 2) Write separate half-reactions for the oxidation and reductions processes. 3) Balance the atoms in the half-reactions. 4) Add enough electrons to one side of each half-reaction to balance the charges. 5) Multiply each half-reaction by an appropriate number to make the numbers of electrons equal in both. 6) Add the balanced half-reactions to show an overall equation. 7) Add the spectator ions and balance the equation.
What is the standard atmospheric pressure in mm Hg? What is it in kPa? (2 points)
The standard atmospheric pressure in mm Hg is 760 mm Hg and 101.3 kPa.
Describe the structure of ice. (3 points)
The structure of ice is a regular open framework of water molecules in a hexagonal arrangement.
What substances dissolve most readily in water? (2 points)
The substances that dissolve most readily in water are ionic compounds and polar molecular compounds.
What is the difference between concentrated and dilute with strong and weak?
The words concentrated and dilute indicate how much of an acid or base is dissolved in solution whereas strong and weak refer to the extent of ionization or dissociation of an acid or base.
What is thermal pollution in ponds? (3 points)
Thermal pollution in ponds is when an industrial plant takes water from a lake to use for cooling and then dumps the warmer water back into the lake causing the entire lake to warm.
A gas occupies 30.0 L at 1.5 atm and 20.0°C. What is its volume at 2.5 atm and 30.0°C? Show your work.
This has to be the combined gas law because we have all three Temperature, Volume and Pressure. Remember Temps are in K (which is +273 from whatever the C is). The Combined Gas Law states: P1 x V1/T1 = P2xV2/T2 so we just plug in and solve for the missing V2. 1.5atm x 30.0L / 293K = 2.5atm x V2 / 303K 303K x 1.5atm x 30.0L / (293K x 2.5atm) = V2 V2 = 18.6L
In the reaction C2H4 + 3O2-->2CO2 + 2H2O, which is the limiting reagent if 2.70 mol C2H4 reacts with 6.30 mol O2? Show your work.
This is asking which one do you not have enough of to use all of the other one. So here it matters the ratio of the two products. which is flippable but is is 1 mol C2H4 / 3 mol O2. If we have 2.70 mol C2H4 X (3 mol O2 / 1 mol C2H4) = we'd need 8.1 mol of O2 to use all of our C2H4 but we only have 6.3 mol of O2 so O2 is limiting how much of the C2H4 we can use and O2 is the limiting reagent.
List three conditions that may alter the color change of an indicator. (3 points)
Three conditions that may alter the color change of an indicator are temperature, dissolved salts, and if the solution being tested is not colorless.
What are three devices used to detect radiation? (3 points)
Three devices used to detect radiation are Geiger counters, scintillation counters, and film badges.
List three properties of gases. (3 points)
Three properties of gases are fills any container, are easily compressed and occupy more space than solids and liquids.
What are three types of nuclear radiation? (3 points)
Three types of nuclear radiation are alpha radiation, beta radiation, and gamma radiation.
Name three unique properties of water that result from hydrogen bonding. (3 points)
Three unique properties of water that result from hydrogen bonding are its high surface tension, low vapor pressure, high boiling point.
Define titration. (2 points)
Titration is the process of adding a measured amount of a solution of known concentration to a solution of unknown concentration.
How do you calculate the specific heat (C) of a substance? (3 points)
To calculate the specific heat (C) of a substance you divide the heat input but the mass of the substance times the temperature change.
Define transmutation. (2 points)
Transmutation is the conversion of an atom of one element into an atom of another element.
What are transuranium elements? (2 points)
Transuranium elements are elements with atomic numbers above 92, the atomic number of uranium.
When you are heating a test tube, you should make sure the mouth of the test tube is pointed away from you and from others.
True
You must wear goggles while cleaning up after an experiment.
True
You should always add concentrated acid slowly to a large volume of water and never the other way around. You should never add water to a concentrated acid.
True
Which of the following statements is incorrect concerning the transfer of chemicals?
You should always return unused chemicals to their original containers.
Calculate the pH of each solution in questions 16-17. Show your work. (8 points, 4 points each) [OH-] = 4.3 × 10-5 M
[H+] = 1.0 x 10-14/4.3 x 10-5 = 2.3 x 10-10 ph = 9.6
Calculate the pH of each solution in questions 16-17. Show your work. (8 points, 4 points each) [OH-] = 8.3 × 10-4 M
[H+] = 1.2 x 10-11 ph = 11
Asymmetric carbon
a carbon with four different atoms or groups attached
Electrolyte
a compound that conducts an electric current when it is in an aqueous solution or in the molten state
Nonelectrolyte
a compound that does not conduct an electric current when in an aqueous solution or the molten state
According to Arrhenius, what distinguishes an acid from a base?
acids produce H+ ions in aqueous solution and bases produce OH- in aqueous solutions
An _____ is a hydrocarbon in which there are only single covalent bonds.
alkane
A hydrocarbon substituent that is derived from an alkane is called an _____.
alkyl group
Strong electrolyte
all or nearly all of the solute exists as ions
Why are all ionic compounds electrolytes?
because they dissociate into ions
Gas pressure is the result of _____ of rapidly moving particles in a gas simultaneously colliding with an object.
billions
One characteristic of bases is that they taste _____.
bitter
When a liquid reaches a boiling point, it causes _____ of vapor to form throughout the liquid.
bubbles
A _____ is a solution in which the pH remains fairly constant when small amounts of acid or base are added.
buffer
The _____ is the amount of acid or base that can be added to a buffer solution before a significant change in pH occurs.
buffer capacity
A hot water or boiling water bath requires which of the following sets of equipment?
burner, wire gauze, iron ring and stand, beaker
The insulated device used to measure the absorption or release of heat in chemical or physical processes is the _____.
calorimeter
_____ is the measurement of the heat transfer into or out of a system for chemical and physical processes.
calorimetry
_____ occurs when electrolytes are introduced into a colloidal system, causing the particles to clump together and settle out from the dispersion.
coagulation
Ammonium nitrate is used in a _____ pack.
cold
_____ have particles larger than those in solutions and smaller than those in suspensions.
colloids
Identify the type of reaction for the following. 2Mg(s) + O2(gas) → 2MgO(s)
combination reaction
Identify the type of reaction for the following. 2K(s) + Cl2(gas) → 2KCl(s)
combination rection
Name the five general types of reactions.
combination, decomposition, single-replacement, double-replacement, and combustion.
Reduction is now defined to mean _____.
complete or partial gain of electrons or loss of oxygen
Enantiomers
pairs of molecules that are mirror images and not superimposable
give an example for each of these colloid systems. Gas-solid
marshmallow
If Kb for water is 0.512°C/m, then what is the boiling point of a solution that contains 1.25 mole CaCl2 in 1400 g of water? Show your work. (3 points)
mass of water = 1.4 kg moles of CaCl2 = 1.25 mol CaCl2 Kb = 0.512 C/m m = 1.25 mol CaCl2 / 1.4 kg = 0.893 m 3 x 0.893 = 2.679m 0.512 C/m x 2.679m = 1.372 C 100C + 1.372C = 101.37C
How many grams of sodium fluoride are needed to prepare a 0.600m NaF solution that contains 600.0 g of water? Show your work.
mass of water = 600.0 g = 0.6000 kg solution concentration = 0.600m molar mass of NaF = 41.98817 g/mol mass of solute = ? g NaF 0.600 mol NaF / 1.000 kg H2O 41.98817 g NaF / 1 mol NaF 0.6000kg H2O x 0.600 mol NaF / 1.000 kg H2O x 41.98817 g NaF / 1 mol NaF = 15.1 g NaF
identify the reactants and the products. methane + oxygen → carbon dioxide + water
methane and oxygen are the reactants and carbon dioxide and water are the products
Only those molecules with a certain _____ can escape from the surface of the liquid during evaporation.
minimum kinetic energy
The enthalpy change caused by a dissolution of one mole of substance is the _____.
molar heat of solution
Calculate the mole fraction of each component in a solution of 42 g CH3OH, 35 g of chloroform CHCl3, and 50 g C3H7OH. Show your work.
molar mass of CH3OH = 32.04 g/mol molar mass of CHCl3 = 119.38 g/mol molar mass of C3H7OH = 60.095 g/mol 42 g CH3OH x 1 mol / 32.04 g CH3OH = 1.311 mol CH3OH 35 g CHCl3 x 1 mol / 119.38 g CHCl3 = 0.293 mol CHCl3 50 g C3H7OH x 1 mol / 60.095 g C3H7OH = 0.832 mol C3H7OH X(CH3OH) = 1.311 mol / (1.311 mol + 0.293 mol + 0.832 mol) = 0.54 X(CHCl3) = 0.293 mol / (1.311 mol + 0.293 mol + 0.832 mol) = 0.12 X(C3H7OH) = 0.832 mol (1.311 mol + 0.293 mol + 0.832 mol) = 0.34
Stereoisomers
molecules in which the atoms are joined in the same order, but the positions of the atoms in space are different
The sign of ΔH is _____ for an exothermic reaction.
negative
Chemists define the pH of a solution as the _____of the hydrogen-ion concentration.
negative logarithm
[OH-] = 1.0 × 10-7 M
neutral
Which of the following is most likely to cause you to start a filtration over again?
overflowing the top edge of the filter paper
Identify each of the following processes as either oxidation or reduction Li LI+ + e-
oxidation
Identify each of the following processes as either oxidation or reduction 2I- I2 + 2e-
oxidation
The substance that gains electrons is the _____ agent.
oxidizing
What is the pH of a solution if [H+] = 0.045 M?
pH = -log H+ pH = -log 0.045 = 1.35
What is the standard heat of reaction (ΔH°) for the formation of NO2(g) from NO(g) and O2(g)? Show your work. (4 points)
ΔHf°NO(g) = 90.37 kJ/mol ΔHf°O2(g) = 0.0 kJ/mol ΔHf°NO2(g) = 33.85 kJ/mol Unknown: ΔH° = ? kJ 2NO(g) + O2(g) --> 2NO2(g) ΔHf°(reactants) = 2 mol NO(g) x ΔHf°NO(g) + 1 mol O2(g) x ΔHf°O2(g) = 2 mol NO(g) x 90.37 kJ/1 mol NO(g) + 1 mol O2(g) x 0kJ/1 mol O2(g) = 180.74 kJ ΔHf°(products) = 2 mol NO2(g) x ΔHf°NO2(g) = 2 mol NO2(g) x 33.85 kJ/1 mol NO2(g) = 67.7 kJ ΔH° =67.7 kJ - 180.74kJ = -113.04kJ