Chemistry Final Study Guide (ch.15-25)
Stoichiometry
(chemistry) conversion factors of ratios that shows the relation between the quantities of substances that take part in a reaction or form a compound (typically a ratio of whole integers)
mole map
****************ideal gas law: PV=nRT **********************/ ****** molar mass **/***** Avogadro's # grams <--------> mole <--------------> particles ******************* I ******************* I balanced equation ******************* I *******molar mass I ******Avogadro's # grams <---------> moles <-------------> particles ***************** / ****************/ ideal gas law: PV=nRT
Temperature corresponding to spontaneity
********exothermic************* endothermic ********** - ***************** **I ******** + *******---------------------------------------- ΔS* + I spon all temp "- +" ****I spon at high "+ +" *******-------------------------------------- **** - I spon at low "- -" ****I never spon "+ -" say along to help rememering: "top row exo(-) endo(+), entropy(ΔS) side plus then minus" for the endo and +ΔS, think HIGH HIGH ++ for the exo and -ΔS think LOW LOW --
Be able to calculate the empirical formula given a percent composition of the elements in a sample of the compound.
- Always ASSUME that there is 100. GRAMS. If you're provided with a sample that has 15.7% carbon, then that means there is 15.7g of carbon. - Convert the grams to moles - If the mole is a decimal like C1.21Cl2.42, then divide the entire compound by the LEAST number. - ^that step should give you CCl2. If you divided a number by the least and still have a decimal like Zr1.5P1O4, then you can multiply everything by two to get it to whole numbers: Zr3P2O8 - If the decimal is SUPER close to being a whole number, then just round it. Ex: Fe1Cl2.999 would be FeCl3 % Composition formula: mass of element/mass of compound x 100
Be able to label a graph of energy vs. reaction progress with reactants, activation energy, products and change in enthalpy.
- Energy vs. reaction progress: energy is on the y-axis and reaction progress is on the x-axis. - Reactant/product: R on the left, P on the right. - Activation energy: Label as Ea, you show it by drawing a vertical arrow showing the distance between the reactant and the highest peak (transitional state). - Change in enthalpy: label ΔH (+ or -); show it by drawing a vertical arrow showing the distance between the REACTANT and the PRODUCT.
Be able to diagram and describe the parts and function of a galvanic cell including the anode, cathode, salt bridge, flow of electrons and ions
- Parts of a galvanic cell: anode, cathode, salt bridge, flow of electrons and ions - function of each part: • The anode is the oxidized half reaction • Cathode is the reduced half reaction • The salt bridge makes sure that the charges on the anode and cathode remain neutral by transferring Cations into the Cathode side and the Anions into the Anode side. This will keep the reaction going. • Electrons always flow from anode to cathode; left to right • The ions (+ or -) will always be in the "water" of the containers brief diagram: *******anode***************cathode reactant I product II reactant I product ^This is the oxidized side. ^This is the reduction side ps. if the solid is not "solid" like solid iodine, you have to use a wire like platinum dipped in the solution
General properties of ACIDS
- Sour - turns litmus paper RED - reacts with metals to form hydrogen gas and a salt - corrosive - electrolyte - pH lower than 7 - proton donor - electron acceptor
Why does adding a second compound to a liquid lower the vapor pressure?
- Vapor pressure decreases when a solute is added. - thus, the boiling point temperature is elevated because solute (added) particles are in the way, making it harder for solvent (the liquid) particles to escape
General properties of BASES
- bitter taste - turn litmus paper BLUE - feels slippery - electrolytes - neutralize acids producing a salt and water - pH higher than 7 - proton acceptor - electron donor
Be able to calculate molarity (M), molality (m), mole fraction (χ), weight percent, and parts per million (ppm).
- molarity: M = moles of solute/liters of solution - molality: m = moles solute/kg solvent - mole fraction: X = (moles of solute)/(moles of solute + moles of solvent) - weight percent: % = (mass of solute/(mass of solute + mass of solvent) )x 100 - parts per million: ppm = (mass of solute/mass of solute + mass of solvent) x (1x10^6)
describe the five states of matter and distinguish between their general properties
- solids: have a definite shape and volume, rigid, cannot be squashed, very dense, strongest attraction between particles - liquids: Definite volume, no definite shape, not rigid, cannot be squashed, less closely compacted than solids, the attraction between particles are not very strong - gasses: No definite shape or volume, not rigid, can be squashed, it is the least closely compacted out of the three common properties, there are no attractions between particles; Take the shape of their containers and can be compressed. - plasma: Gas composed of cations and free electrons. exotic but it's everywhere, highly conductive, low pressure and high temperature - Bose-Einstein condensate (manmade): A state of matter in which separate atoms or subatomic particles, cooled to near absolute zero temperature (0 K, -273.15 C, or -459.67 F).
How to predict the change in Entropy?
- the side of the equation with the most molecules (or atoms) in the gaseous state has the highest entropy. - if no gases are present, then the side with the highest number of molecules in the liquid or aqueous state has the highest entropy. - if only solids are present, then the side with the highest number of molecules has the highest entropy.
Examples of colligative properties of solutions
- vapor pressure - osmotic pressure - boiling point - freezing point
Basic conversion factors
1 L = 1,000 mL 1 mL = 1 g 1 kg = 1,000 g 1 kJ = 1,000 J one mole of any gas at STP(standard temperature and pressure) has 22.4L of that gas for the Molarity: M = mol/L so, a 2.70M would = 2.70mol/L
Be able to explain how the concentration, temperature, surface area, and addition of a catalyst affect reaction rate.
1. Concentration: When we increase the concentration of one type of molecule, it increases the likelihood of collision between reactants that will react together. 2. Temperature: - add heat, or energy to everything - all of the molecules gain kinetic energy - more molecules will now be able to crest the hill - activation energy remains the same - speed up ALL reactions in a system - increase the likelihood of collisions - increase the speed of collisions - allow reacts to have sufficient energy to reach the activated complex and form the required transitional state - increase the number of molecules that have the energy to reach the activated complex 3. Surface area: Increasing it will expose more area for collision to occur. 4. Catalyst: It decreases the activation energy and creates good reaction geometry.
The Three Laws of Thermodynamics are:
1. Energy cannot be created or destroyed 2. The disorder (entropy) of the universe is increasing. Disorder is all about the spreading out of energy. 3. A perfect crystal at zero Kelvin has zero entropy. (Every molecule moves, so it has entropy. At 0 kelvin nothing will be able to move, so the entropy will be zero)
types of crystalline solids
1. molecular: - Held together by intermolecular forces - composed of molecules - poor ability to conduct electricity - low melting point examples: water, sugar 2. ionic: - Held together by ionic bonds - composed of ionic compounds - poor electricity conductor - melting point is high example: salts 3. metallic: - Held together by "sea of electrons" or metallic bonding - composed of metal cations - good electricity conductor - melting points are variable example: gold 4. network covalent: - Held together by covalent bonds - composed of atoms - poor electricity conductor - melting point is very high example: diamond
How to make a solution
1.calculate the mass of materials needed for the solution 2.weigh the mass of materials 3.place into a VOLUMETRIC FLASK 4.add distilled water to 1 L mark 5.stir/shake and label with molarity and chemical formula
[H3O+]=[OH-], or pH + pOH =
14 ex: If you are given or find a value of pH such as 4, then you know the pOH must be 10 because the sum of those two are = to 14 pH = -log [concentration of H+] [H+] = 10^-pH
Suspension
A heterogeneous mixture that separates into layers over time. particles: - diameter is > 1,000 nm - will settle - (Tyndall effect)
PV = nRT example
A 2.5L cylinder contains 0.60 mol of nitrogen gas at 25°C. What is the pressure of the gas inside of this cylinder? P = nRT/V P = (0.60)(0.08206)(25+273.15)/(2.5) = 5.9atm
Solution
A MIXTURE that forms when one substance dissolves another.
Solvent
A liquid substance capable of DISSOLVING OTHER substances
Empirical formula of a compound example
A dry-cleaning compound was decomposed into 14.5 g carbon and 85.5 g chlorine. In a separate experiment, its molar mass was determined to be 166.0 grams. ASSUME it's 100 grams: 14.5 + 85.5 = 100 (perfect hehe) What is the empirical formula of the compound? 14.5g C x (1mol C/12.011g C) = 1.21mol C 85.5g Cl x (1mol Cl/35.453 Cl) = 2.42mol Cl The least number of this compound is 1.21. Divide the entire compound by 1.21: (C1.21Cl2.42)/1.21 = CCl2 this would be the EMPIRICAL formula. What is the molecular formula of the compound? At the beginning of the problem, we were given that the compound's molar mass is 166.0 grams Calculate the molar mass of CCl2: it's 82.9161g 82.9161g is about half of 166.0g, so that means we need to DOUBLE the empirical formula: C2Cl4
State function
A function that depends only on the initial and final states of a system, not on the path in between.
Be able to distinguish between positive and negative energies with respect to heat transfer in and out of a system.
A negative sign means it is releasing heat; heat going OUT; exothermic. A positive sign means it is gaining heat; taking IN heat; endothermic. First law of thermodynamics: Energy can be transferred and transformed, but it cannot be created or destroyed. q in = -q out OR expressed as: q in + q out = 0
Limiting reactant
A reactant that is totally consumed during a chemical reaction, limits the extent of the reaction, and determines the amount of product.
Crystaline solid
A solid that is made up of crystals in which particles are arranged in a regular, repeating pattern
enthalpy
A thermodynamic equivalent to the total heat content update system at constant pressure; it is the amount of heat/energy transferred. It can be positive or negative. ΔH = q
Be able to name and recognize the formulas of simple acids and bases.
Acid formulas typically contain hydrogen ions: H+ Base formulas typically contain hydroxide: OH- ps. also, acid-base reactions produce a SALT and WATER
Moles of reactants and to moles of products example
Always make sure the equation is BALANCED Let's say we have 24.0 grams of H2. How many moles of NH3 will it make? N2 + 3 H2 --> 2 NH3 24.0g H2 • (1mol H2/2.016g H2) • (2mol NH3/3mol H2) = 7.94mol NH3
Define Arrhenius and Bronsted-Lowry acid and bases.
Arrhenius acid: Substances that produce hydrogen ions. H+ when dissolved in water HCl --> H+ + Cl- Arrhenius base: substances that produce hydroxide ions. OH- when dissolved in water NaOH --> Na+ + OH- Bronsted-Lowry acid: proton donor Bronsted-Lowry base: it is a proton acceptor (for the Bronsted-Lowry think H+ has an extra one, so it DONATES to OH- who will gladly ACCEPT it!)
Be able to calculate average reaction rate and instantaneous reaction rate from a graph for both reactants and products.
Average rate: Use the slope formula to calculate the slope of 2 points (x1, y1) and (x2, y2): m = y2-y1 / x2-x1 (Take the value absolute value) Instantaneous rate: How to find it: 1. Draw a tangent to the graphed data so that the tangent line touches just one tiny spot on the graph 2. Calculate the slope of the tangent line and that will be the rate at that specific point.
Gas stoichiometry example: In the following reaction of a common cleaner, how many moles of hydrogen gas are produced when 0.230g of Al react with an excess of NaOH? Al(s)+ NaOH(s)+ H2O(l) → H2(g) + NaAlO2(aq)
BALANCE: 2 Al(s)+ 2 NaOH(s)+ 2 H2O(l) → 3 H2(g) + 2 NaAlO2(aq) We are given that the limiting reactant is aluminum, so we can go ahead and start with aluminum. 0.230g Al x (1mol Al/26.981538g Al) x (3mol H2/2mol Al) = 0.0128mol H2 Q pt2: How many milliliters of H2 measured at STP is this? 0.0128mol H2 x(22.4L/1mol H2)x(1000mL/1L) = 287mL H2
M1V1=M2V2
Formula used to determine how to create a solution of desired concentration from a stock solution of known Molarity and volume
Units of heat
Calories and joules 1 calorie = 4.18 joules
If we titrate 75.00 mL of H3PO4 with 35.42 mL of 1.20 M KOH, what is the concentration of H3PO4? Show your work. H3PO4 (aq) + 3 KOH (aq) → K3PO4 (aq) + 3 H2O (l)
Check if it's balanced first. It isss! 3 SIGFIGS from the word problem: 1.20M 35.42mL KOH x (1L/1,000mL) x (1.20mol KOH/1L) x (1mol H3PO4/3mol KOH) = 0.0142mol H3PO4 75.00mL = 0.07500L (0.0142mol H3PO4)/(0.07500L) = 0.189M H3PO4
Excess or limiting reactant example
Copper reacts with sulfur to for copper(I) sulfide according to the unbalanced equation: Cu(s) + S(s) → Cu2S(s) What is the limiting reactant when 80.0 g Cu reacts with 25.0 g S? ALWAYS BALANCE FIRST: 2 Cu(s) + S(s) → Cu2S(s) 80.0g Cu x (1mol Cu/63.546g Cu) x (1mol CuS2/2mol Cu) x (159.158g CuS2/1mol CuS2) = 100.g CuS2 25.0g S x (1mol S/32.066g S) x (1mol CuS2/1mol S) x (159.158g CuS2/1mol CuS2) = 124g CuS2 In this case, COPPER(I) is the limiting reactant because it produced the LEAST amount of product. THEORETICALLY SPEAKING, 100.g of CuS2 is what it SHOULD make if we were in the Garden of Eden :p In the real world we probably won't have exactly 100 grams of CuS2.
Name covalent/ionic compounds
Covalent: Use the prefix system -mono -di- tri -tetra -penta -hexa -hepta -octa -nona -deca Prefix + name (mono not used of 1st element) Then prefix + root + "ide" on second element Ionic: Use full name of metal (positive ion). Use roman numerals for transition metals with varying oxidation states. Use root of nonmetal (negative ion) add "ide"
Why is it important to have a balanced chemical equation in stoichiometry?
Doing this will obey the Law of Conservation of Mass. Whatever you have in the reactant, you will have the same amount leftover in the product. Having the correct stoichiometry will allow you to correctly predict the amount of a certain product it produces.
Be able to calculate cell electrode potentials of a galvanic from the table of Standard Reduction Potential values and predict if the reaction will be spontaneous or nonspontaneous.
E°cell: look at the table and find the value for the reduction and add the value of the oxidation. remember, you must FLIP THE SIGN of the oxidation value. If E°cell is positive (+), then the reaction will be spontaneous. If E°cell is negative (-), then the reaction will be nonspontaneous.
Fahrenheit to Celsius
F = 1.8C+32 Be able to isolate C using basic math: C = (F - 32)/1.8
Remember the significant figure rules
For adding or subtracting: the number should have the least decimal place. ex: 45.7 + 22.432 = 68.1 (=68.132 but it has to be rounded to the 10's decimal place For multiplying or dividing: keep the least number. ex: 20 • 215 = 4000 (=4300 but rounds down for 1 sigfig) (20 has 1 sigfig bc it doesn't have a decimal place like 20. Otherwise it would be 2 sigfigs)
Condensation
Gas to liquid
Be able to solve problems involving stoichiometry and ΔH° to determine the amount of energy a certain mass can produce and vice versa. Ex: How many kilojoules of energy are consumed when 15.0 grams of BaO2, barium oxide, decomposes? Hint: This is a Stoichiometry problem. 2 BaO2(s) → 2 BaO(s) + O2(g) ΔH°rxn = +161.6 kJ
Given: 2 BaO2(s) → 2 BaO(s) + O2(g) (balanced) ΔH°rxn = +161.6 kJ and 15.0g of BaO2 15.0g BaO2 x (1mol BaO2/169.3258g BaO2) x (161.6 kJ/2mol BaO2) = 7.16kJ ps. ΔH°rxn = +161.6 kJ means it's that amount of energy for EACH part of the equation. Like: 161.6 kJ/2mol BaO2 161.6 kJ/2mol BaO 161.6 kJ/1mol O2 etc. kJ could be in the bottom mor mol at the top, it's just a conversion factor.
Be able to describe and represent mathematically and graphically Boyle's Law, Charles' Law, Avogadro's Law and Guy Lussac's Law.
Help for remembering (ignore the stars): *************Boyle ****************P **\ Avogadro **n V ****> Gay Lussac's ****************T **/ *************Charles Each law have 2 variables. B: P&V C: V&T A: n&V GL: P&T The constants of each law are the variables that the law doesn't have in PV = nRT (except R, the constant). Ex: Boyle's law (PV=k) constants are n and T. Also, Boyle's law is the only INVERSE relationship.
Colloid
Heterogeneous mixture that is cloudy and uniform in appearance. particles: - diameter is 1 nm < x < 1,000 nm - don't settle - light scatters
Be able to describe reaction rate changes due to concentration and surface area with respect to the number of collisions.
High concentration = Faster rate; more collisions Low concentration = Slower rate; less collisions Lots of surface area = Faster rate; more collisions Little surface area = Slower rate; less collisions
Describe the relationship between the cell's potential and Gibb's Free Energy
In a galvanic cell, the Gibbs free energy is related to the potential by: ΔG° = −nFE°cell. If E°cell > 0, then the process is spontaneous (galvanic cell). PS. (you'll probably be given this but just in case) F = 96,485 coulombs per mole (C/mol)
Order the phases of matter with respect to increasing entropy
Least entropy to greatest entropy: solid, liquid, gas
How do we know how much of the excess reactant will be left over after the reaction in 80.0 g Cu reacting with 25.0 g S? 2 Cu(s) + S(s) → Cu2S(s)
In the previous problem, we found that copper is the limiting reactant, so that automatically makes sulfur the excess reactant. To find out how much excess reactant is left over, we need to use up ALL of the LIMITING REACTANT. That is 80.0g of Cu. 80.0g Cu x (1mol Cu/63.546g Cu) x (1mol S/2mol Cu) x (32.066g S/1mol S) = 20.2g S 20.2g of S is how much it is USED. To find out how much it has left over, we subtract the amount USED up from the original amount: 25.0 - 20.2 = 4.8g S (only 2 sigfigs bc we only have 1 decimal place) 4.8g S is the amount LEFT OVER
Calculate theoretical yield, actual yield, and percent yield.
In the previous problem, we had 7.94mol of NH3. That's the THEORETICAL yield. Let's say that in the lab we made 6.42mol NH3. That would be the ACTUAL yield. The percent yield: (actual/theoretical)x100 PERCENT yield is (6.42/7.94) x 100 = 80.9%
What is a mole?
It is a measuring unit. It is 6.022 x 10^23 of SOMETHING. You can have a mole of pens, shoes, AnYtHiNg! Scientists and chemists use it to measure the number of atoms or any particles. On the periodic table, the molar mass of each element is in g/mol (grams per mole).
Celsius to Kelvin
K = C + 273.15
Calculate the molar mass of an atom
Let's say we have 1.00 atom of carbon. Use the conversion 1 mol of atom = 6.022x10^23 atoms. We have to go from atom of C to mole of C, then to grams of C. 1.00 atom C • (1mol C/6.022x10^23 atom C) • (12.011g C/1mol C) = 1.99x10^-23g C *Extra for how to do the 6.022x10^23 on TI84 calculator: 1. Put open parentheses ( 2. Type 6.022 3. Hit 2nd (the blue button at the top left) 4. Hit the button that looks like a comma "," above #7, or it says "EE" above the button. 5. Punch in 23 6. Close parentheses ) 7. You're good to go!
Vaporization
Liquid to gas
Gay-Lussac's Law: type of relationship and the constants
P/T = k - P&T - directly related, so the graph is at a positive slope/rate - As T increases, P increases - Constant: n, V
Boyle's Law: type of relationship and the constants
PV = k - P&V: inversely related, so the graph is at a negative slope/rate - As P increases, V decreases - Constants: T, n
Ideal Gas Law
PV = nRT P = pressure in atmospheres (atm) V = volume in liters (L) n = number of moles (mol) R = gas constant (0.08206 L•atm/mol•K) T = temperature in Kelvin (K)
Be able to know the
Polyatomic ions (sulfate SO4 2-, nitrate NO3- etc.) and their charges. (refer to the table of polyatomic ions or my previous quizlet)
colligative properties
Property of solution that depends only on the NUMBER of solute particles present in the solution, NOT what kind of solute
Be able to identify a redox reaction, the element being oxidized, and the element being reduced. EX: Which element is being oxidized in this reaction? 2 KClO3 (s) → 2 KCl (s) + 3 O2 (g)
Redox reaction is when there is one element that became more positive in the product and another element became more negative in the product. The element being oxidized is the one that became more positive. REACTANT: KClO3 We first figure out the charge of everything. KClO3: the first rule we can use is Group 1 metal. K = + 1 O = - 2 (oxygen rule) (use algebra to find Cl; the whole compound is neutral) 0 = Cl + 1 + 3(- 1) 0 = Cl - 2 +2 = Cl PRODUCTS: KCl and O2 KCl: Gr 1 metal K = +1 Cl must be = -1 bc it's a neutral element. O2 is diatomic so it's 0 let's see the final image: K: +1 --> +1 SAME Cl: +2 --> -1 REDUCED O: -2 --> 0 OXIDIZED (this is the answer for the Q!)
Be able to assign oxidation states for each element in a given compound.
Rules of assigning oxidation states: Must sign the charge in THIS ORDER 1. Is it a neutral Element or a diatomic molecule? 0 2. Is it a Monoatomic ion? ion's charge 3. If it's a group 1, 2, 3 Metal, Ag+, Cd2+, or Zn2+ : ion's charge 4. Transition metal: wait and look for the anion 5. Non diatomic Fluorine (bonded to something): -1 6. Hydrogen: +1 7. Oxygen (when not bonded to a metal, F, or H): -2 8. Other: use algebra to solve "Every Man Must Form His Own Opinion"
Tyndall effect
Scattering of a light beam as it passes through a colloid
Calculate the molar mass of a compound
Simply add the molar mass of each element. The molar mass of each element is the number under each element. ex: find the mm of CuSO4. Cu - 63.546 g/mol S - 32.066 g/mol O - 15.999 g/mol 63.546 + 32.066 + 4(15.999) = 159.608 g/mol (you're adding, so use the add/subtract sigfigs rule: keep the least number of decimal place)
Define spontaneous reaction, entropy, Gibb's Free Energy
Spontaneous reaction - A reaction or process that needs NO outside intervention to keep it going Entropy - Disorder. Disorder is all about the spreading out of energy. Gibb's Free Energy - ΔG; usable energy Negative ΔG means the reaction is spontaneous Positive ΔG means the reaction is NOT spontaneous.
Solute
Substance BEING dissolved
Standard Temperature and Pressure (STP)
Temperature: 273.15 K or (0°C) Pressure: 1.00 atm Volume: 1 MOLE of ANY gas at STP has a volume of 22.4L
specific heat
The heat required to raise the temperature of 1 gram of water by 1 degree Celsius HIGH specific heat means it takes HIGHER temperature to heat up. Ex: wooden pencil is hard to heat up. LOW specific heat means it doesn't take as much heat to heat up; easy to heat up. Ex: metal heats easily
Excess reactant
The reactant that is not completely used up in a chemical reaction, meaning there are some leftovers after the reaction.
Be able to explain the action of a catalyst with respect to activation energy and collision theory.
They create an alternative pathway for a reaction by lowering the Activation Energy (least amount of energy required of reactants in order for them to react) of a reaction. That means more molecules will be able to reach the activation energy because it doesn't require as much energy as it would without it, so that speeds up the reaction. Whatever the catalyst may be, it will draw-in the reactants so that they react, but the catalyst itself remains chemically unchanged at the end of a reaction.
Be able to calculate how temperature affects reaction spontaneity.
To find the temperature at which the reaction SWTICHES to spontaneous you... Substitute ZERO in the place of ΔG° in the equation ΔG° = ΔH° - TΔS° 0 = ΔH° - TΔS° solve for T
If I had 0.280L of a 6.00M solution of HCl and added enough water to lower the concentration to 4.50M, what would my new volume be?
Use M1V1 = M2V2 M1 = 6.00M V1 = 0.280L M2 = 4.50M V2 = ? (6.00M)(0.280L) = (4.50M)V2 V2 = (6.00M)(0.280L) / (4.50M) V2 = 0.373L (3 Sigfigs)
Charles' Law: type of relationship and the constants
V/T = k - V&T: directly related, so the graph is at a positive slope/rate - As T increases, V increases as well - Constants: P, n
Avogadro's Law: type of relationship and the constants
V/n = k - V&n: directly related, so the graph is at a positive slope/rate - As V increases, the n of moles increases as well - Constants: P, T
vaporization vs evaporation
Vaporization is the phase change of molecules. Evaporation occurs when the vapor pressure is lower than the atmospheric pressure.
Be able to balance oxidation and reduction half-reactions with respect to charge and atoms. EX: Consider the single replacement reaction of zinc with copper (II) sulfate solution. Find: a. the chemical equation for this reaction b. the net ionic equation for this reaction c. the two balanced half-reactions (including electrons) corresponding to the net ionic equation, identifying which process each describes
We are giving that it is a SINGLE replacement. The word "with" you can treat it as add. The word "solution" you know it's aqueous. Also, only pair cations with anions. Zinc: Zn (s) Copper (II) sulfate solution: CuSO4 (aq) ((II) means that copper has a +2 charge, and SO4 has a -2 charge, so the change for the compound is neutral.) a. Zn (s) + CuSO4 (aq) ---> ZnSO4 (aq) + Cu (s) b. Zn(s) + Cu2+(aq) + SO4 2- (aq) → Cu(s) + Zn2+(aq) + SO4 2- SO4 2- (aq) is on both sides, so it cancels out: Net ionic equation: Zn(s) + Cu2+(aq) → Cu(s) + Zn2+(aq) c. Oxidized half reaction: Zn (s) ---> Zn2+ (aq) + 2e- Reduced half reaction: Cu2+ (aq) + 2e- ---> Cu (s)
How serial dilutions were carried out
With the most concentrated solution, draw let's say 3mL from the 15mL solution. Put the 3mL in a new container and add enough water to make it 15mL. Draw 3mL from the mew one and put it into a new container. This repeats and the solutions get less and less concentrated.
Determine whether a process or reaction is spontaneous with respect to ΔH and ΔS. EX: Calculate ΔG at 298K for the following reaction. NH4Cl(s) → NH3 (g) + HCl (g) The ΔHrxn = +176kJ and the ΔSrxn = +285 J/(mol•K)
You need to know Gibb's free energy equation for this kind of problem: ΔG° = ΔH° - TΔS° The preferred unit is kJ, so if it's in J we need to convert it to kJ. We need to convert ΔSrxn = +285 J/(mol•K) S° = 285 J x (1kJ/1,000J) = 0.285kJ ΔH° = 176kJ T = 298K ΔG° = (176) - (298)(0.285) = 91kJ ps. If ΔHrxn and ΔSrxn is given, then you can ignore the given chemical equation. If ΔHrxn and ΔSrxn are not given, then you MUST figure ΔHrxn and ΔSrxn out individually.
How to identify which one is the limiting or excess reactant?
You will be given a chemical equation with a certain amount for each reactant. Do the stoichiometry for each reactant to find out how much product it will produce. If the product side have more than one product, then just pick one of the products to use for each reactant. The reactant that makes the least of the product will be the limiting reactant.
Be able to apply stoichiometry to reactions in solution. EX: When 45.0 mL of 2.73 M HCl reacts with excess zinc metal, what volume of H2 gas (in liters) forms at STP? Show your work. Zn (s) + 2 HCl (aq) → ZnCl2 (aq) + H2 (g)
Zn (s) + 2 HCl (aq) → ZnCl2 (aq) + H2 (g) It's balanced We are only concerned with how to get to moles of H2. Given 45.0mL of 2.73M HCl reacts with zinc. 45.0mL HCl x (1L/1,000mL) x (2.73mol HCl/1L) x (1mol H2/2mol HCl) = 0.0614mol H2 PV = nRT we need volume: V = nRT/P at STP -> P = 1.00atm, T = 273.15 k (or 0°C), R always = 0.08206 V = nRT/P V = (0.0614)(0.08206)(273.15)/(1.00) = 1.38L H2 PS. The final sigfigs depends on the least sigfigs IN the word problem. EX: if the words had a number like 41, then it would have 2 sigfigs even though we started the stoichiometry with 45.0mL that has 3 sigfigs
Viscosity
a liquid's resistance to flow. ex: honey has a high one because it flows slowly, and water has a low one because it flows easily.
critical point
a point on a phase diagram when: the temperature and pressure at which the density of liquid and gasses phases of a substance are identical.
it will take higher temperature to boil a liquid in...
areas with a high pressure. (low elevation areas)
name acids
binary acids: named using the format "hydro_____ic acid" - replacing the blank with the stem name of the anion ex. HCl -> hydrobromic acid H3P -> hydrophosphoric acid H2S -> hydroponic acid
amorphous solid
describes a solid that lacks an ordered internal structure; denotes a random arrangement of atoms
Be able to represent energy diagrams for endothermic and exothermic reactions graphically.
endothermic graph (ignore the stars): *******------- *******I *******I ------- think step up + exothermic graph (ignore the stars): ---------- *********I *********I *********------------ think step down -
Deposition
gas to solid
Cohesion
intermolecular forces that bind SIMILAR molecules to one another ex: water attracting water molecules
Adhesion
intermolecular forces that bind a substance to a surface, one substance attracting to a DIFFERENT substance. ex: water molecules sticking to a glass container
Freezing
liquid to solid
Acid-base stoichiometry route
molarity x volume of known solution --> moles of known solution --> equation stoichiometry --> moles of unknown --> molarity of unknown
Dilution occurs when
more solvent is added to a solution
The Van't Hoff factor accounts for all of the...
number of pieces the compound breaks into. ex: NaCl is soluble, so it dissociates into Na+ and Cl-, so there are a total of 2 pieces. A sugar molecule like C6H12O6 will not dissociate, so it will be 1.
Be able to read the
periodic table: -The elements are assigned in order by the protons. -Electronegativity/electro affinity (how much an element wants to GAIN electrons) INCREASES from left to right, bottom to top. Fluorine is the most electronegative for reference. -Groups (columns) 1(+1), 2(+2), 13(+3), 15(-3), 16(-2), 17(-1), 18(0) have definite charges. Group 14 has a ±4 charge. Groups 3-12 are the transition metals, so their charges can vary. Ag is always +1, Cd and Zn are always +2. -Valence electrons (e- on the outer ring) of the element depends on the column they're on. First column has 1 e-, gr 2 has 2 e-, (skip the transition metals) group 13 has 3 e-, gr 14 has 4 e-, gr 15 has 5 e-, gr 16 has 6 e-, gr 17 has 7 e-, and gr 18 has 8 e-(gr 18 are the happy noble gasses with an octet).
q = m • c • ΔT
q = m • c • ΔT q: amount of heat absorbed (+) or released (-) in J or cal m: mass in g or kg c: specific heat of a substance (J/g • °C) ΔT: change in temperature (T final - T initial)
Be able to calculate the heat released or absorbed using the equation q = mcΔT. Ex: In order to cook an omelet, a 5.00 kg iron skillet must be heated from room temperature (25.0°C) to 150.0°C. How many Joules of heat must be used to accomplish this? The specific heat capacity of iron is 0.4521 J/g°C.
q = m • c • ΔT q = ? m = 5.00kg c = 0.4521 J/g°C ΔT = 150.0°C - 25.0°C q = (5.00kg)(0.4521 J/g°C)(150.0°C - 25.0°C) = 283kJ = 283,000J ps. g in kg cancels with g in J/g°C, °C cancels out, so we're left with kJ
Sublimation
solid to gas
Melting
solid to liquid
capilary action
tendency of water to rise in a narrow tube due to adhesion when liquid goes up a narrow tube against the force of gravity - that's how plants absorb water throughout the stems and leaves
surface tension
the force needed to spread out liquid molecules
Vapor pressure is the pressure of
the gas particles above its liquid in a closed container
Stock solution
the most concentrated solution in the series
triple point
the temperature and pressure conditions at which the solid, liquid, and gaseous phases of a substance coexist at equilibrium
Boiling occurs when
the vapor pressure from a liquid is equal to the atmospheric pressure.
calculate ΔH° rxn using the thermodynamics table
ΔH° rxn = ΣnΔH° products - ΣnΔH° reactants sum of the products: (number of moles)(energy of the bond) MINUS sum of the reactants: (number of moles)(energy of the bond) ex: 6 CO2 + 6 H2O -> C6H12O6 + 6 O2 [1(-1275)+6(0)] - [6(-394)+6(-242)] = [-1275 + 0] - [-2364 -1452] = 2541 KJ
ΔTb = Kb ∙ m ∙ i example: The boiling point elevation of a solution made by dissolving 12.2 g of KCl in 45.0 g of water is_______. Show your work. Kb = 0.512 °C/m and Kf = -1.86 °C/m
ΔTb = Kb ∙ m ∙ i Given: Kb = 0.512°C/m To figure out m: convert grams of KCl to moles, and grams of water to kg. m = mol solute/ kg solvent. To figure out i: figure out if the compound is soluble. If it is, figure out how many pieces it dissociates into. 12.2g KCl x (1mol KCl/74.511g KCl) = 0.164mol KCl 45.0g H2O x (1kg/1,000g) = 0.0450kg H2O (0.164mol KCl)/0.0450kg H2O = 3.64m KCl i = 2: KCl is soluble. KCl --> K+ + Cl- (2 pieces) ΔTb = (0.512)(3.64)(2) = 3.73 °C ΔTb is positive, so we ADD that to the normal boiling point, which is 100°C. 100.00°C + 3.73°C = 103.73°C ps. in the equation ΔTb = Kb ∙ m ∙ i i's number does not count for sigfigs. Also, i's number on the test shouldn't be more than 3.
boiling point elevation equation
ΔTb=Kb • m • i ΔTb is the change in boiling point Kb is the molal boiling point constant m is the molality of solution i is the Van't Hoff factor ps. boiling point constant of water is 0.512 °C/m (usually given)
freezing point depression equation
ΔTf = Kf ∙ m ∙ i ΔTf is the change in freezing point Kb is the molal freezing point constant m is the molality of solution i is the Van't Hoff factor Ps. freezing point constant of water is -1.86 °C/m (usually given)
Calculate ΔH, ΔS, or ΔG of a chemical reaction.
Δ___°rxn = [ΣnΔ___° product] - [ΣnΔ___° reaction]
Define oxidation, reduction, oxidation state, reducing agent, oxidizing agent, redox reaction.
• Oxidation - the LOSS of electrons in a chemical reaction. • Reduction - the GAIN of electrons in a chemical reaction. • Oxidation state - shows how many electrons have been lost from atom or gained by the atom. • Reducing agent - substance that causes another chemical to be REDUCED. It itself is being oxidized. • Oxidizing agent - substance that causes another chemical to be OXIDIZED. It itself is being reduced. • Redox (reduction-oxidation) reaction- Any chemical reaction in which the oxidation number of a molecule, atom, or ion change by gaining or losing electrons. The reaction involves the TRANSFER OF ELECTRONS.
Define reaction rate, transition state, activated complex, activation energy, collision theory
• Reaction rate - rate = change/time • Transition state - The molecules are in a state where the bonds are partially formed. The highest energy point on a diagram. • Activated complex (transition state) - an unstable arrangement of atoms that exists momentarily at the peak of the activation-energy barrier; an intermediate or transitional structure formed during the course of a reaction. • Activation energy - The minimum quantity of energy the reactant must possess in order to undergo a specific reaction. • Collision theory - Chemical reactions occur ONLY WHEN the collision of the reactants is at the right SPEED and GEOMETRY.
Be able to choose the appropriate gas law to calculate the final pressure, temperature, or volume of a gas when given the initial conditions. There are four types.
• gas law type 1 (no reaction occurs)- find the value of the missing term: PV = nRT • gas law type 2 (no reaction occurs)- find the value of the missing term when the conditions change: P1V1/T1 = P2V2/T2 • gas law type 3 (reaction occurs)- find the amount of product produced with gases involved: use the mole map and Ideal Gas Law (PV = nRT) • gas law type 4 (mixture of gases)- total pressure or moles will equal the sum of the pressure or moles of the individual gases
