Chemistry B
Ammonia (NH3 (g), Hf = -45.9 kJ/mol ) reacts with oxygen to produce nitrogen and water (H2 O(g), Hf = -241.8 kJ/mol) according to the equation below. What is the enthalpy of the reaction?
-1,267.2 kJ
The enthalpies of formation of the compounds in the combustion of methane, are CH4 (g): Hf = -74.6 kJ/mol; CO2 (g): Hf = -393.5 kJ/mol; and H2 O(g): Hf = -241.82 kJ/mol. How much heat is released by the combustion of 2 mol of methane?
-1,605.1 kJ
Manganese dioxide (MnO2(s), Hf = -520.0 kJ) reacts with aluminum to form aluminum oxide (AI2O3(s), Hf = -1699.8 kJ/mol) and manganese according to the equation below. What is the enthalpy of the reaction?
-1,839.6 kJ
Ethyne (C2 H2 (g), Hf = 226.77 kJ/mol) undergoes complete combustion in the presence of oxygen to produce carbon dioxide (CO2 (g), Hf = -393.5 kJ/mol ) and water (H2 O(g), Hf = -241.82 kJ/mol) according to the equation below. What is the enthalpy of combustion (per mole) of C2 H2 (g)?
-1255.6 kJ/mol
Propane (C3 H8 (g), Hf = -103.8 kJ/mol) reacts with oxygen to produce carbon dioxide (CO2 , Hf = -393.5 kJ/mol ) and water (H2 O, Hf = -241.82 kJ/mol) according to the equation below. What is the enthalpy of combustion (per mole) of C3 H8 (g)?
-2,044.0 kJ/mol
The combustion of glucose, C6 H12 O6 (s), produces carbon dioxide, CO2 (g), and water, H2 O(g), according to the equation below. C6H12O6(S)+6O2(G) - 6CO2(G)+6H2O(L) The enthalpy of the reaction is -2,840 kJ. What is the heat of combustion, per mole, of glucose?
-2,840 kJ/mol
Carbon reacts with oxygen to produce carbon dioxide (CO2 (g), Hf = -393.5 kJ/mol) according to the equation below. C(S)+2O2(G) - CO2(G) What is the enthalpy change of the reaction?
-393.5 kJ
A 150 mL sample of hydrochloric acid (HCl) completely reacted with 60.0 mL of a 0.100 M NaOH solution. The equation for the reaction is given below. HCl + NaOH - NaCl + H2O What was the original concentration of the HCl solution?
0.040 M
The molar mass of KCl is 74.55 g/mol. If 8.45 g KCl are dissolved in 0.750 L of solution, what is the molarity of the solution?
0.151 M
A chemistry teacher adds 50.0 mL of 1.50 M H2SO4 solution to 200 mL of water. What is the concentration of the final solution?
0.300 M
A scientist is examining a mixture of nitrogen, hydrogen, and ammonia. The individual pressures that are exerted by nitrogen and hydrogen are 0.26 atm and 0.28 atm, respectively. If the total pressure is 0.90 atm, what is the partial pressure of ammonia?
0.36 atm
A copper rod that has a mass of 200.0 g has an initial temperature of 20.0°C and is heated to 40.0°C. If 1,540 J of heat are needed to heat the rod, what is the specific heat of copper?
0.385 J/(gi°C)
A chemist uses 0.25 L of 2.00 M H2SO4 to completely neutralize a 2.00 L of solution of NaOH. The balanced chemical equation of the reaction is given below. 2NaOH + H2SO4 - Na2SO4 + 2H2O What is the concentration of NaOH that is used?
0.50 M
How many moles of Ba(NO3)2 are there in 0.25 L of a 2.00 M Ba(NO3)2 solution?
0.50 mol
The pOH of a solution is 10.75. What is the concentration of OH- ions in the solution?
1.778 x 10-11 M
Considering radiation weighting factors only, how many times more dangerous are alpha particles than protons?
10
What is the equilibrium constant of pure water at 25°C?
10-14
Note the pH and pOH values labeled with letters on the pH scale below. Based on log rules and the way pH is calculated, what is the difference in [OH- ] concentration between point A and point B.
10^6
Consider the equation for the formation of water. 2H2 + O2 - 2H2O What is the theoretical yield of H2O if 130 g of H2O is produced from 18 g of H2 and an excess of O2?
160 g
The chemical equation below shows the formation of aluminum oxide (Al2O3) from aluminum (Al) and oxygen (O2). 4Al + 3O2 - 2Al2O3 The molar mass of O2 is 32.0 g/mol. What mass, in grams, of O2 must react to form 3.80 mol of Al2O3?
182
In a group assignment, students are required to fill 10 beakers with 0.720 M CaCl2. If the molar mass of CaCl2 is 110.98 g/mol and each beaker must have 250. mL of solution, what mass of CaCl2 would be used?
200 g
Consider the reaction. Based on the equation and the information in the table, what is the enthalpy of the reaction?
226.73 kJ
The graph below shows how solubility changes with temperature. How many grams of NaCl will be needed to form 600 mL of a saturated solution at 100°C?
240 g
A chemist dilutes a 1.0 mL sample of 2.0 M KNO3 by adding water to it. If the concentration of the solution that is obtained is 0.0080 M, what is its volume?
250 mL
A sample of hexane (C6H14) has a mass of 0.580 g. The sample is burned in a bomb calorimeter that has a mass of 1.900 kg and a specific heat of 3.21 J/giK. What amount of heat is produced during the combustion of hexane if the temperature of the calorimeter increases by 4.542 K?
27.7 kJ
Terry, a student, performs a titration. He completes these steps as part of his titration procedure: 1. He cleans and rinses a burette with standardized base. 2. He fills the burette with standardized base solution. 3. He reads and records the initial burette volume. 4. He adds a base from the burette to an acid. 5. He observes a color change in the Erlenmeyer flask. 6. He stops the addition of base from the burette. 7. He reads and records the final burette volume. Which steps will provide information needed to calculate the volume of base needed to reach the equivalence point?
3 and 7
An acid has an acid dissociation constant of 2.8 x 10-9. What is the base dissociation constant of its conjugate base?
3.6 x 10-6
A sample of octane (C8H18) that has a mass of 0.750 g is burned in a bomb calorimeter. As a result, the temperature of the calorimeter increases from 21.0°C to 41.0°C. The specific heat of the calorimeter is 1.50 J/(g • °C), and its mass is 1.00 kg. How much heat is released during the combustion of this sample?
30.0 kJ
A student takes a measured volume of 3.00 M HCl to prepare a 50.0 mL sample of 1.80 M HCl. What volume of 3.00 M HCl did the student use to make the sample?
30.0 mL
Complete combustion of a 0.600-g sample of a compound in a bomb calorimeter releases 24.0 kJ of heat. The bomb calorimeter has a mass of 1.30 kg and a specific heat of 3.41 J/(gi°C). If the initial temperature of the calorimeter is 25.5°C, what is its final temperature?
30.9°C
Consider the generic chemical equation below. X + Y - W + Z Reactant X contains 199.3 J of chemical energy. Reactant Y contains 272.3 J of chemical energy. Product W contains 41.9 J of chemical energy. If the reaction loses 111.6 J of chemical energy as it proceeds, how much chemical energy must product Z contain?
318.1 J
The pH of lemon juice at 298 K is found to be 2.32. What is the concentration of H3O+ ions in the solution?
4.79 X 10^-3 M
The pH of lemon juice at 298 K is found to be 2.32. What is the concentration of H3O+ ions in the solution?
4.79 x 10^-3
The initial temperature of a bomb calorimeter is 28.50°C. When a chemist carries out a reaction in this calorimeter, its temperature decreases to 27.45°C. If the calorimeter has a mass of 1.400 kg and a specific heat of 3.52 J/(gi°C), how much heat is absorbed by the reaction?
5,170 J
A student prepares 150.0 mL of 1.40 M HCl using 35.0 mL of a stock solution. What is the concentration of the stock solution?
6.00 M
In a school's laboratory, students require 50.0 mL of 2.50 M H2SO4 for an experiment, but the only available stock solution of the acid has a concentration of 18.0 M. What volume of the stock solution would they use to make the required solution?
6.94 mL
The graph below shows how solubility changes with temperature. What is the solubility of Na2HAsO4 at 60°C?
65 g/100 mL of water
Nitrogen dioxide, a major air pollutant, can be produced by the combustion of nitrogen oxide as shown. 2NO + O2 - 2NO2 In a plant, 1,500 kg of nitrogen oxide is consumed per day to produce 1,500 kg of nitrogen dioxide per day. What is the percent yield?
65.2%
The chemical equation below shows the decomposition of ammonium nitrate (NH4NO3). NH4NO3 - N2O + 2H2O A chemist who is performing this reaction starts with 160.1 g of NH4NO3. The molar mass of NH4NO3 is 80.03 g/mol; the molar mass of water (H2O) is 18.01 g/mol. What mass, in grams, of H2O is produced?
72.06
Which graph represents an exothermic reaction?
A
Which of the glassware shown below is an Erlenmeyer flask?
A
How does litmus paper identify a base?
A base turns red litmus blue.
A substance with a high pOH would likely have which of the following?
A high [H+ ] and a low pH
A gaseous substance turns into a solid. Which best describes this change?
A substance that has no specific volume changes to a substance that has a specific volume.
What is the Arrhenius definition of an acid?
A substance that increases H3O+ concentration when it is dissolved in water.
Based on the definition of logarithms, what is the difference in hydrogen ion concentration between a substance with a pH of 2 and a substance with a pH of 3?
A substance with a pH of 2 has a 10 times higher concentration of H+ than a substance with a pH of 3.
Consider the equation below. AgNO3(aq) + NaCl(aq) - AgCl(s) + NaNO3(aq) Which compound is the precipitate in this chemical reaction?
AgCl
Which of the following best defines an acid?
An acid has more hydrogen ions in solution.
Which of these accurately describes why an acid is strong?
An acid is strong when it dissociates completely in water.
Which statement is true for most chemical reactions?
An energy change occurs during the breaking and forming of bonds.
Look at the diagram below. Which best describes what is taking place in the diagram?
An indirect measurement of pH is taking place.
A substance is dissolved in water and produces hydronium ions. This occurs when hydrogen ions move from the substance to associate with water molecules. Which term best matches the behavior of this substance?
Arrhenius acid
Which term describes a substance that increases the concentration of hydroxide ions in solution?
Arrhenius definition of a base
Which diagram is a bomb calorimeter?
B
Which equations shows the complete dissociation of a strong base?
BOH+H2O - B+ + OH- + H2O
Which substance is a strong electrolyte?
Ba(OH)2
An ice cube is dropped into a glass of milk at 20°C. Which statement explains the transfer of kinetic energy (KE)?
Because milk has higher KE than ice, KE is transferred from the milk to the molecules of ice.
Which piece of glassware shown below is used to hold and dispense a solution of known concentration during a titration?
C long one
An acid is a substance that increases the concentration of H3O+ ions in solution. Look at the reaction below of phenol (C6H5OH) with water: C6H5OH(aq) + H2O(l) - C6H5O-(aq) + H3O+(aq) Which reactant acts as an acid by contributing a H+ ion to create H3O+ in the chemical equation?
C6H5OH(aq)
Consider the incomplete reaction below. NaOH + X - NaCH3COO + H2O What is X in this reaction?
CH3COOH
Which is an example of dissociation?
Ca3(PO4)2 - 3Ca2+ + 2PO43-
Which are produced when HCl reacts with Ca(OH)2?
CaCl2 and H2O
Consider the reaction below. Fe(s) + CuSO4(aq) - Cu(s) + FeSO4(aq) Which reactant is a substance that is dissolved in solution?
CuSO4
Which compound will conduct electricity when it is dissolved in water?
CuSO4
Which is a biological effect of low exposure to radiation?
DNA damage
Which statement describes the law of conservation of energy?
Energy cannot be created nor destroyed, but it changes from one form to another.
Reactant P contains 50 J of energy, and reactant Q contains 35.3 J of energy. The reactants combine to form product PQ, which contains 104 J of energy. What is the energy transformation?
Energy is absorbed because the product has more energy than the reactants have.
According to the law of conservation of energy, what will most likely happen in a closed system?
Energy will be exchanged, but matter will not be exchanged.
Shown below is a chemical reaction. Fe + CuCl2 - FeCl2 + Cu Which pair of substances are the products?
FeCl2 and Cu
Which equation represents the total ionic equation for the reaction of HNO3 and NaOH?
H+ + NO3- +Na+ +OH- - Na+ + NO3- + H2O
Consider the chemical equation below. Mg(OH)2+2HNO3 - Mg(NO3)2+2H2O Which is the net ionic equation?
H+ + OH- - H2O
Consider the reaction below. H2PO4- + H2O - H3O+ + HPO42- Which of the following is a base-conjugate acid pair?
H2O and H3O+
Which of the following would most likely act as a Bronsted-Lowry acid?
HCN
Consider the reaction below. HF + H2O - H3O+ + F- Which is an acid-conjugate base pair?
HF and F-
Chemical energy in burning wood is changed into thermal energy. The thermal energy is absorbed by water, which boils to produce steam. The thermal energy is changed into kinetic energy in the moving steam. The kinetic energy is used to turn a turbine, which converts the kinetic energy into electricity. Which sentence best describes this system?
It involves both energy transformation and energy transfer.
Which statement describes the Arrhenius interpretation of acids and bases?
It is limited to situations that involve aqueous solutions or specific compounds.
Which statement best describes the pH of pure water?
It is neutral because the concentration of hydronium ions equals that of hydroxide ions.
Which statement best describes a Bronsted-Lowry base?
It must accept protons to form a conjugate acid.
Which characteristic best identifies an Arrhenius base?
It must generate hydroxide ions in water.
Which is a characteristic of a weak electrolyte?
It partially dissociates or ionizes in water.
Which statement would indicate the presence of an acid?
It reacts with active metals to form a gas.
Which statement describes how a basic coffee cup calorimeter works?
It uses the mass and specific heat of water along with a thermometer to measure the gain or loss of energy when a substance is added.
Which units express specific heat capacity?
J/(gi°C), J/(giK), cal/(gi°C), cal/(giK)
How does the value of Ka and Kb compare with the concentrations of hydronium ion and hydroxide ion?
Ka x Kb=[H3O+][OH-]
What happens to energy when Sally kicks a soccer ball?
Kinetic energy is transferred from the leg to the soccer ball.
A compound accepts electrons from another substance to form a covalent bond. Which term best describes this compound's behavior?
Lewis acid
Which step accurately describes how to measure the final burette volume?
Locate the bottom of the meniscus and record volume to the nearest 0.01 mL.
A generator contains a coil that spins to produce an electric current. How is energy transformed by using a generator?
Mechanical energy is transformed to electromagnetic energy.
Which statement is correct?
Most salts are ionic and are soluble in water.
Consider the reaction below. HClO3 + NH3 - NH4+ + ClO3- Which is a base-conjugate acid pair?
NH3 and NH4+
What is the pH of a solution with [H+] = 1.25 x 10-10 M?
NOT -10.1
Butane (C4 H10(g),g Hf = -125.6 kJ/mol) reacts with oxygen to produce carbon dioxide (CO2 , Hf = -393.5 kJ/mol ) and water (H2 O, Hf = -241.82 kJ/mol) according to the equation below. What is the enthalpy of combustion (per mole) of C4H10 (g)?
NOT -509.7 kJ/mol -5315.0 kJ/mol
Given that the molar mass of NaNO3 is 85.00 g/mol, what mass of NaNO3 is needed to make 4.50 L of a 1.50 M NaNO3 solution?
NOT 18.9 g
What is the net ionic equation for the reaction that is represented by the following total ionic equation?
NOT C 2PO3-/4
Which reaction would produce a solution that conducts electricity extremely well?
NOT CH3CH2OH(l) - CH3CH2OH(aq)
Consider the total ionic equation below. What are the spectator ions in this equation?
NOT H+ and Ba2+
Consider the reaction below. Zn(s) + 2HCl(aq) - H2(g) + ZnCl2(aq) Which product is a substance that is dissolved in solution?
NOT HCl
Which reaction displays an example of an Arrhenius base?
NOT HCl(g) + H2O(l) - H3O+(aq) + Cl-(aq)
A patient comes into the hospital because she is worried about possible exposure to radiation. The doctors determine that the patient has 60 rem of exposure. What is her risk of cancer?
NOT High because her exposure is less than 100 rem.
Which statement about Hf is true?
NOT It is negative when a compound forms from elements in their standard states.
If the base-dissociation constant, Kb, for a substance is 4.3 X 10-10, what does this tell you about Ka?
NOT Ka = 2.3 X 10^2
The specific heat of water is 4.18 J/(gi°C) and that of wood is 1.97 J/(gi°C). Which statement is correct?
NOT Regardless of mass, water will heat up less than wood if the same heat is added.
Which statement correctly describes the Ka of a weak acid?
NOT The Ka is large, and the equilibrium favors products. NOT The Ka is large, and the equilibrium favors reactants.
Hydrogen reacts with chlorine to form hydrogen chloride (HCl (g), Hf = -92.3 kJ/mol) according to the reaction below. Which statement is correct?
NOT The enthalpy of the reaction is -184.6 kJ, and the reaction is endothermic.
What does it mean for a weak acid to be in equilibrium?
NOT The position of equilibrium in weak acids lies more to the right than to the left. NOT At equilibrium there is a small amount of HA and more A- and H+.
Which statement is true if the Hrxn of a reaction is positive?
NOT The reaction is exothermic.
Which is true of weak acids and bases?
NOT They dissociate completely in water.
Shown below is an ion from a salt molecule. Which statement best explains the event?
NOT This is the formation of electrolytes during ionization.
How is enthalpy used to predict whether a reaction is endothermic or exothermic?
NOT When the enthalpy of the products is higher than the enthalpy of the reactants, the reaction is exothermic.
Which is a way to express concentration of a solution?
NOT force per square meter
Under which conditions would the solubility of a gas be greatest?
NOT high pressure and high temperature
A base is added to an acid during a titration. A pH meter is used to monitor the reaction's progress. When should the addition of base stop?
NOT when adding a few milliliters of base causes a large increase in pH
Which represents a double replacement reaction and would occur?
Na2CO3(aq) + CaCl2(aq) - 2NaCl(aq) + CaCO3(s)
The graph below shows how solubility changes with temperature. Which two solutions have similar solubilities at 40°C?
Na2HAsO4 and Na2SO4
Use the following table to answer the question. Which of these is a neutral salt?
Na2SO4
Which salt is produced when H2SO4 reacts with NaOH?
Na2SO4
The two products that are formed when a solution of HNO3 and a solution of NaOH react are water and
NaNO3.
Maya, a student, performs a titration. She completes the following steps as part of her titration procedure. 1. She cleans and rinses a burette with base solution. 2. She fills the burette with standardized base solution. 3. She adds a base from a burette to an acid. 4. She observes a color change in the Erlenmeyer flask. 5. She continues to add more base. Based on the above procedure, will she obtain accurate results?
No, because she did not stop adding base once the color changed.
Which is a difference between the focus of a nuclear engineer and the job of a nuclear chemist?
Nuclear engineers are concerned with the design, construction, and operation of nuclear reactors; nuclear chemists study nuclear reactions, radioactive elements, and nuclear power.
Which formula represents a double displacement reaction?
Pb(NO3)2(aq) + 2HCl(aq) - 2HNO3(aq) + PbCl2(s)
What is the difference between the units rem and rad?
Rem is used to measure biological risk, and rad is used to measure absorbed radiation.
Which statement best describes why specific heat capacity is often more useful than heat capacity for scientists when comparing two materials?
Specific heat capacity is an intensive property and does not depend on sample size.
A base is added to water. What happens when the position of equilibrium lies to the left?
The base is partially dissociating into products.
If hydrofluoric acid is a stronger acid than acetic acid, which statement is most likely true?
The conjugate base of hydrofluoric acid is weaker than that of acetic acid.
What does it mean for a strong acid to be in equilibrium?
The equilibrium lies far to the right so that products are very heavily favored.
An arrow is fired at a target on a high wall. Which statement correctly describes the change in the energy of the arrow as it moves toward the target?
The kinetic energy decreases as potential energy increases.
The pH of a solution is 2.0. Which statement is correct?
The pOH of the solution is 12.0.
A book is falling from the top shelf of a bookcase. Which statement correctly describes the change in the energy of the book?
The potential energy decreases as kinetic energy increases.
What is the relationship between Ka and Kb with Kw?
The product of Ka and Kb equals the auto-dissociation constant for water.
The Hrxn of formation of carbon dioxide is negative. Which statement is true?
The reaction is exothermic.
Which is true about dissolving a polar substance in water?
The solute particles are carried into the solution.
H2SO4 is added to a large beaker of water. How is the solution different from the original water?
The solution turns blue litmus to red.
Which statement best explains the change that occurs when gas particles move more slowly?
The temperature decreases because the average kinetic energy decreases.
Which is an advantage of using chemical indicators?
They are inexpensive to use.
What do strong acids and strong bases have in common?
They both dissociate completely, with little or no reverse reactions.
Which is a property of acids in aqueous solutions?
They increase the concentration of H+ ions.
Which is a disadvantage of using chemical indicators?
They must be selected for a narrow pH range.
Water is called the "universal solvent." Which statement best explains this description with respect to ionic compounds?
Water can dissociate many ionic compounds through ion-dipole interactions.
Which is most likely true about water in chemical systems?
Water dissociates ionic compounds.
Which best explains why water has a much higher boiling point than would otherwise be predicted?
Water forms strong hydrogen bonds.
Which statement accurately describes part of the dissolving process of a polar solute in water?
Water molecules surround solute molecules.
Consider the reaction 2AI(OH)3 + 3H2SO4 - X + 6Y. What are X and Y?
X = AI2(SO4)3; Y = H2O
Which represents the empirical formula for X4Y8?
XY2
The table shows the characteristics of four substances after they are placed in water. Which compound is most likely the strongest electrolyte?
Y
Which chemical reaction involves the production of a gas?
Zn(s) + 2HCl(aq) - H2(g) + ZnCl2(aq)
Which of these substances contributes to soap's slippery texture?
a base
A 1-L soda bottle contains dissolved carbon dioxide gas. Which bottle would have the highest concentration of dissolved gas?
a bottle that is sealed
What is the Bronsted-Lowry definition of a base?
a compound that accepts protons
What is the Bronsted-Lowry definition of an acid?
a compound that donates protons
Which statement defines calorimeter?
a device that measures the heat that is gained or lost in a chemical change
Which best describes the definition of Lewis acids and bases?
a general definition based on electron structure
A solution containing HCl would likely have
a low pH and a high pOH.
Which of these refers to the concentration of an acid?
a measure of quantity of acid dissolved in water that is designated by molarity
Which describes a precipitate in a chemical reaction?
a solid product formed from aqueous reactants
A solution conducts an electric current more easily when the solution contains more ions. An acidic solution conducts an electric current very easily. What type of acid is in this solution?
a strong acid because it dissociates completely
What is the definition of a Lewis acid?
a substance that accepts electrons to form a covalent bond
Which instrument is most often used to measure acid volume before a titration begins?
a volumetric pipette
An aqueous solution is made from a molecular compound rather than from an ionic compound. If some ions are present in solution, which best describes the solute?
a weak electrolyte
Consider the temperature versus time graph below. At what temperature is the substance a heated gas?
above 100°C
Which type of radiation is blocked by the skin but is the most dangerous once it is inside the body?
alpha particles
The main active components of bleach and many other household cleaners are
bases.
Which type of radiation do people try to protect themselves from by wearing protective clothing that is made of aluminum?
beta radiation
H2CO3 is used in soft drinks. What is the name of this compound?
carbonic acid
Old photographic flashbulbs burn magnesium metal in a reaction that causes a flash of brilliant white light. A photographer would need to take care not to suffer burned fingers when trying to replace the hot bulb. What best identifies the energy transformation that occurs in the flashbulb?
chemical energy to electromagnetic energy and thermal energy
In which process do ionic compounds separate into their oppositely charged constituent ions when they are dissolved in water?
dissociation
When ammonium chloride is dissolved in water, the beaker gets cold. Which type of reaction does this describe?
endothermic
The enthalpy of formation for C6 H6 (I) is 49.0 kJ/mol. Consider the following reaction. Is the reaction endothermic or exothermic, and what is the enthalpy of reaction?
endothermic; Hrxn = 49.0 kJ
What would be the greatest difference in using an open ceramic coffee mug rather than an insulated mug with a lid as a calorimeter?
exchange of energy with the surroundings
Which type of radiation travels at the speed of light and penetrates matter easily?
gamma rays
Which is the best example of potential energy?
holding a basketball in the air
Which compound plays an important role in leather processing and electroplating?
hydrochloric acid
A chemical equation can be used to solve stoichiometry problems provided that it
includes the coefficients that are needed for balancing the equation.
Which of these factors will cause a solid solute to dissolve faster?
increasing the surface area of solute
Which term refers to the formation of ions as a result of a chemical reaction?
ionization
An unknown substance turns methyl orange solution red. This shows that the substance
is an acid.
A chemist dissolved crystals of an unknown substance into water at room temperature. He found that 33 g of the substance can be dissolved into 100 mL of water. What property of the unknown substance was the chemist most likely investigating?
its solubility
The heat capacity of a sample should be divided by which quantity to find the specific heat capacity?
mass in grams
Which career is most concerned with the study of radioactive isotopes?
nuclear chemist
Which describes the polarity in a water molecule?
partial negative charge on the oxygen atom because it pulls electrons from the hydrogen atoms
What form does the radiation that is used to treat cancer take?
photons
For an experiment, a student needs a compound that has the following properties. • It dissolves in water. • It is an electrolyte. • It is excellent conductor of electricity. Which substance would be the best choice for the experiment?
potassium chloride
As gravity makes an object fall down toward the ground, energy becomes kinetic energy.
potential
Which best defines concentration?
ratio that describes the amount of solute divided by the amount of solvent or solution
Which household item uses radiation in a beneficial way?
smoke detectors
Which pair of substances would most likely result in the production of a solid when reacting with a base?
soluble metal salt and carbon dioxide
Under which conditions will sugar most likely dissolve fastest in a cup of water?
sugar crystals with stirring at 15°C
A beaker contains a solution. A single solute crystal is added to the solution. Immediately, crystals form in the solution. Which term best describes the solution before the crystal was added?
supersaturated
The concentration of a solute in a solution is greater than the maximum concentration that is predicted from the solute's solubility. What is the best way to describe this solution?
supersaturated
Which defines the average kinetic energy of a system's particles?
temperature
Which factor influences both solubility and the rate of dissolution?
temperature
A chemist lectures about the following definition for acids and bases. The acid-base behavior is analyzed in terms of how electrons are transferred between compounds rather than in terms of how hydrogen ions are transferred. What is the chemist defining?
the Lewis concept of acids and bases
The reaction below demonstrates which characteristic of a base? CuSO4(aq)+2NaOH(aq) - Cu(OH)2(s)+Na2SO4(aq)
the ability of a base to react with a soluble metal salt
Which statement describes thermal energy?
the energy that is associated with temperature
Which of these correctly defines the pH of a solution?
the negative log of the hydronium ion concentration
The equivalence point in a titration refers to the point when
the number of moles of one reactant reacts completely with the moles of the other reactant.
Which substance loses electrons in a chemical reaction?
the one that is oxidized, which is the reducing agent
Which statement defines specific heat capacity for a given sample?
the quantity of heat that is required to raise 1 g of the sample by 1°C (Kelvin) at a constant pressure
Which statement defines the heat capacity of a sample?
the quantity of heat that is required to raise the sample's temperature by 1°C (or Kelvin)
Which statement describes mechanical energy?
the sum of the kinetic energy and the potential energy of an object
A weak base is added to water. Which information is required to find the strength of its conjugate acid?
the values of Kb and Kw
Nonelectrolytes fail to ionize or dissociate in water because
they are very strongly bonded to each other.
Why is citric acid added to food?
to add tartness
Which of these is the main goal of any titration?
to determine the concentration of one of the reactants
Which of the following is the main reason to use titration in chemistry?
to find the molarity of an unknown acid or base
A chemist is about to perform a titration by adding a base to an acid. What is the most important reason for using a base instead of water to rinse out the burette?
to prevent dilution of the base, which may affect the results
A chemist has dissolved a certain substance in water. The chemist knows that more of the substance could be dissolved into the water before it stops dissolving. Therefore, the current solution is
unsaturated
When are drops of indicator most likely added to the Erlenmeyer flask?
when preparing to measure pH change
At what point is a base no longer added during a titration?
when the pH increases suddenly in the flask
