WARNING / WARNING / EXTREME DANGER / ONLY LOOK HERE AFTER YOU HAVE ATTEMPTED THE PROBLEM FOR YOURSELF AND CHECKED THE ANSWER

----update 12/9/25 ----

Marathon Problem
From the summer work
e) The tough part here is it skipped what would have been a helpful step. Use some of what you do in (c) or start over with the 8.76 grams of water to get grams of H.
Now, using the CO2 produced solve for the grams of C in original liquid.
Once you know grams of H and C, the only element left is O

f) This is an interesting situation regarding the empirical formula. As you work through it you'll get 1.5 carbons. The empirical formula is the lowest whole number ratio so we need to keep the pattern of C1.5H3O but make them whole numbers. To get 1.5 to a whole number we multiply by 2 and apply that to the entire pattern.

i) The heat that came out of the unknown went into water. It is that last sentence of the intro. paragraph. Focus on that water and use the q=mc(delta)T equation.

j) Heat of combustion is the energy / mol. In this case kJ of heat / mol of unknown burned. Take the heat from part i and make it negative (this indicates it released heat). Then, divide by the moles of unknown.

k) If you try to draw a Lewis structure from the molecular formula and you stick to organic molecules you can draw a Carboxylic Acid and an Ester.

l) Esters are known to have a property mentioned in the intro. paragraph.

***From here on is not summer work***
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Chapters 1 - 3
Page 23, 48, 71
Page 71 #41) Hint Level 1 use the amount of CO2 to get the moles of C, use the amount of H2O to get the moles of H, then what is left of the 5.000g is the Cl
Hint Level 2 when solving for moles of H, note that 1 mol H2O contains 2 mol of H
Hint Level 3 at the end you have to multiply 5 to get the correct subscripts
#45) look at your hydrate lab from last year
#75) you need to do a percent problem then a density problem then a stoichiometry problem
#89) Hint Level 1 write separate reactions for the production of calcium oxide and calcium nitride
Hint Level 2 write a reaction for the production of calcium hydroxide
Hint Level 3 use the amount of calcium hydroxide to find the amount of calcium oxide
Hint Level 4 use the amount of calcium oxide to find the amount of calcium that turned into CaO
Hint Level 5 use the amount of calcium that turned into CaO to find the amount of calcium that turned into Ca3N2
Hint Level 6 use the amount of calcium that turned into Ca3N2 to find the amount of calcium nitride

Page 49, 69-70, 72
Page 69-70 Summary Problem
a) you may have to look at your notes from last year
Page72
#44) similar to the DDT from last HW
#46) this looks at a hydrate a little different from the last HW, do the % problem first then use that to help solve for mass of MgSO4

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Chapter 6 & 7
Review of electron config. / periodic properties WS
#4) valance electrons are the same as outer shell electrons
#10) you need to consider both the periodic trend of atomic radius and what happens when an atom gains or loses electrons
#17) be sure to adjust for the charge
#22) has multiple correct answers

Page 157
#1a) convert the wavelength into meters
#1c) convert the J into kJ and convert the single photon into a mol of photons
#31) "abbreviated" is the same as shorthand
#49d) remember to remove the "p" and then "s" before the inner "d" electrons

Page 159
#71b) for the proof that n4 to n2 will have a longer wavelength than n5 to n2 you need to solve for the energy of each transition, then use the two equations at the top of page 5 lecture notes to solve for the wavelength.

Page 190
#1c) if you do orbital diagrams you can see why the double bond should be on O and not Cl
#19a) yep, B only gets 6 electrons
#19b) see lecture notes
#19c) combo of odd e- and an ion, fun
#21a) be sure to show resonance

Page 192
Be sure to do Lewis structure first

Ch 6-7 WS #1
#9) back to kJ and for just one single electron
#16-21) be sure to give a thorough explanation
#26) Hint Level 1 630nm is the wavelength
Hint Level 2 convert 630nm to meters
Hint Level 3 use speed of light equation to solve for frequency
Hint Level 4 use the equation with Plank's constant to solve for energy

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Chapter 5 & 9
Gas Laws Review WS
#1) you will need the chart with vapor pressure of water and temperature (it is in the book and in notes)
#5) multistep problem
Hint Level 1 you will need the chart again to get just the pressure of the gas (without water vapor)
Hint Level 2 solve for moles of gas (PV=nRT)
Hint Level 3 use definition of molar mass
#6) Graham's Law equation (the one with velocity)
#8) need that chart again

Page 125
#11) combined gas law and assume all dry ice sublimes
#17) PV=nRT
#33a) PV=nRT for N2O5 then stoichiometry to get H+
#37) Hint Level 0 assume 100 grams
Hint Level 1 find the moles of each gas and the total moles of gas
Hint Level 2 do a mole ratio for each gas
Hint Level 3 the mole ratio for each gas is the moles of that gas / total moles of gas
Hint Level 4 ratio must be multiplied by the total pressure
#39) Hint Level 1 find the moles of wet gas and also the moles of dry gas using PV=nRT for each
Hint Level 2 find the moles of water by subtracting
Hint Level 3 find the pressure of water using either mole fraction or PV=nRT
#43b) Hint Level 1 find the moles of acetylene
Hint Level 2 use the moles of acetylene to find the moles of products (stoichiometry, but include both products)
Hint Level 3 find pressure of products using PV=nRT
#43c) do a mole ratio for each of the gases based on the reaction and your answer in #43b to get partial pressure of each product

Page 127
#49) Hint Level 1 use Graham's law with molar mass of each gas
Hint Level 2 you are solving for the velocity of NO (it has wierd units of moles)
Hint Level 3 the velocity of N2O4 given in the question, if you assume one second, is actually .0129 mol / sec

Ch 5&9 WS #1
#1c) We are looking for a comparison between the speed of those gas molecules. Start with Graham's law and solve it for the question of speed of H2 over speed of H2O. Let the molar masses fall into place then insert their numbers, then serve and enjoy..

Ch 5&9 WS #2
#1a) get total moles then PV=nRT
#1bi) keep as a fraction, no need to solve
#1c) think about the size of the two gas molecules
#1e) Hint Level 1 find the limiting reactant
Hint Level 2 find the moles of O2 left and add to the mol of NO2 produced
Hint Level 3 plug the total moles into PV=nRT
#4dii) "root-mean-square" means square root in this case (you can use Graham's law and adjust to compare the speeds of the molecules) or just use logic based on the size of the molecules and the resulting speeds
#6) Hint Level 1 use molar masses for m1 and m2
Hint Level 2 use .100mol / 52.0s for the velocity of Hydrogen
Hint Level 3 use .100mol / ?s for the velocity of Chlorine

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Chapter 8 & 17
deltaH, deltaS, deltaG Review (first year) worksheet
#4) remember to keep the coefficient of C4H10 as 1 (for combustion reactions)
#5) it is a mole problem and do stoichiometry as if energy was one of the chemicals
#6) same hint as #5
#7) remember to form the compound from its elements or diatomics only
#9) remember to keep the coefficient of compound formed as 1 (for formation reactions)
#10) Hint Level 1 you need a mathmatical equation for this, then look at the sign of your answer
Hint Level 2 you need the formula that relates deltaH, deltaS, and delta G
#13) you need a mathmatical equation for this (but different than #10)
#14) Hint Level 1 there are two steps that you must solve for seperately
Hint Level 2 add the two steps together
Hint Level 3 the 1st step is q=mcdeltaT and the 2nd step is a phase change mole problem
#15) Hint Level 1 compare the given (desired) reaction to the reaction for combustion of C3H8
Hint Level 2 the desired reaction is just the reverse of the combustion of C3H8
#16) Hint Level 1 (start with two combustion reactions)
Hint Level 2 (one of the combustion reaction is for C7H16 and the other is for C)
Hint Level 3 (the combustion reaction for C is C + O2 ---> CO2)
Hint Level 4 (the C7H16 reaction will remain normal and the C reaction will get flipped and multiplied by 7)

Page 219 (& notes page 30)
Notes page 30 is just like the prior example on the bottom of page 29, use table 8.4
#5a) the MgSO4 is dissolving into water (so, just split up the ions)
#5c) if 1.51 kJ of heat is evolved (so -1.51 kJ), the heat going into the water (qH2O) is +1,51kJ
#5d) Hint Level 1 q=mcdeltaT for amount of heat into water
Hint Level 2 then add temp. change to initial temp
#7c) turn grams into moles, then divide the energy from b by the moles
#17b) grams into moles, then moles NH3 to kJ (but the -637 becomes +637 because the reaction is going backwards)
#19b) PV=nRT, then moles O2 into kJ using the thermochemical equation
#25a) temp. change so q=mcdeltaT (technically you are solving for q, not deltaH)
#25b) phase change so grams into moles, then moles into energy (technically your solving for q, not deltaH)
#25c) Hess law using answers from a and b

Page 221
#37) do summation like in the lecture notes
#77) solve for q into the bomb calorimeter, then switch the sign, then use that to solve for grams, then percent

Page 468
#25) you will probably get an answer of +231.2kJ but it needs to be divided by 2 because the reaction has 2 CH3OH (technically deltaG is based on 1 mol of the chemical)
#29a) use the given values and the formula deltaG=deltaH - TdeltaS
#29b) use the answer from a and do summation with the S values in the chart
#29c) use deltaH from the question and do summation with the H values in the chart

Page 469
#33) see page 458, table 17.2
#35) deltaG=deltaH - TdeltaS, and set deltaG as zero
#49) deltaG° by summation then Q then deltaG
#53a) deltaG° by summation
#53b) Hint Level 1 solve for Q, then solve for the O2 value
Hint Level 2 solve for Q using deltaG=deltaG°+RTlnQ, which will equal 1.100x10(25), then using the Q expression plug in x for the O2 value, and solve for x
#55) use deltaG values like Hess law
#59) you need to find how many moles of ATP must react in order for the other reaction (dG of +372kJ) to also react
#65) equilibrium K so deltaG=0 and Q becomes K, then solve for deltaG°
#80b) use deltaG=deltaH - TdeltaS to think about what it must be, you can also see table 17.2 in the book
#80c) same hints as #80b
#80e) use deltaG=deltaG°+RTlnQ but at equilibrium and solve for K

Ch 8 & 17 Review WS
#1c) consider how the change in deltaG (in #1b) would shift the reaction, then how that would affect the K
#1d) nonspontaneous means deltaG is 0
#2) in other words, which of the three chemicals would be the most abundant?
#3a) Hint Level 1 use Hess law and the three reactions
Hint Level 2 the third reaction will need to be flipped and divided by 3
Hint Level 3 the second reaction will need to be flipped and divided by 6, and the first reaction divided by 2
#3b) summation using the S values given
#3c) deltaG=deltaH - TdeltaS
#3d) deltaG=deltaG° + RTlnQ, set deltaG=0, change Q to K, and plug in answer from #3c as deltaG°
#4) deltaG=deltaH - TdeltaS and set deltaG=0
#9) (like the lab) q=mcdeltaT for the solution, then change the sign, then divide by moles of NaOH

Page 223 #76
a) summation
b) Hint Level 1 use q=mcdeltaT
Hint Level 2 you are solving for deltaT
Hint Level 3 the answer from (a) is the q but make it positive
Hint Level 4 solve for the mass • specific heat for the aluminum oxide, then for the Iron, then add them and continue with q=mcdeltaT
Hint Level 5 use molar mass for the mass of aluminum oxide and for Iron
Hint Level 6 because the q is relative to the reaction you will need to double the mass of of Iron (like it is in the reaction)
Hint Level 7 the q is in kJ but the specific heats are in J so I recommend converting the specific heats into kJ
c) look at the melting point of Fe and the answer of (b)

Ch 8 & 17 Practice Test
#7a) (like in the notes) remember positive enegy to break reactant bonds and negative energy when product bonds form
#7b) summation
#7c) deltaG=deltaH - TdeltaS
#8b) grams C3H8 to moles then to kJ using the heat of combustion of propane, then switch sign, then q=mcdeltaT
#9a) combine the mass of water and solute for the mass in q=mcdeltaT
#9b) use just the mass of solute when solving for moles

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Chapter 10
Page 276
#3) Hint Level 1 "assume 100g solution," so 5.00g CH3COOH and 95.00g H2O
Hint Level 2 turn grams of vinegar into moles and grams of solution into volume using the density, then solve for Molarity
#15) "assume 100g solution," so 85.0g H3PO4 and 15.0g H2O
#17a) just like the lesson notes
#17b) "assume 100g solution," so 30.0g KOH and 70.0g H2O, and just like the lesson notes
#9c) Hint Level 1 problem is weird because the mass% and mole fraction is for the solvent (not the solute)
Hint Level 2 "assume 100g solution," so 85.5g solvent (H2O) and 14.5g solute (caffeine)
Hint Level 3 ppm is "parts per million" so grams solute / grams solution, then x 1,000,000

Page 277
#11a) solve for grams of K2Cr2O7 and say what to do with it
#11b) use dilution equation to solve for starting volume of given solution and say what to do with it
#13a) molarity question
#13b) use dilution equation to solve for final molarity of Al2(SO4)3 then split it into ions
#19a) hydrogen peroxide has hydrogen bonding so more polar so more like water
#19b) NaOH is ionic, silicon dioxide is covalent network
#19c) HCl ionizes (similar to ionic), chloroform is organic
#19d) methyl alcohol has hydrogen bonding, methyl ether does not have hydrogen bonding
#21a) summation using table 8.3 on page 207 (and you thought we were done with summation)
#23a) convert atm to mmHg but notice it is on the bottom of the unit fraction
#23b) Henry's Law
#23c) Hint Level 1 use molarity from #23b and volume to solve for moles of Helium then
Hint Level 2 ideal gas law to solve for volume of Helium

Solution Formation WS
#1) use the second method from the notes to solve for deltaH of solution
#2) read the two pages (598 & 599) in the packet of worksheets
#3) water is polar, carbon tetrachloride is nonpolar

Page 278
#27a) you are given the mole fraction of the solute but you need the mole fraction of the solvent, so "assume 1 mol total" and now if you subtract the mole fraction of solute from 1 mol total you get the mole fraction of solvent
#27b) "assume 100g solution"
#27c) "assume 1 kg of solvent"

Page 278 again
#37) solve for molality of acetone then FP and BP
#43) Hint Level 1 C6H6 is the solvent. C10H10 is the solute.
Hint Level 2 solve for molality of C10H10 then grams of C10H10 then % benzene

Chapter 10 Review WS
#5) the pressure needs to be in atm because of "R"
#6) their are two versions of Henry's law, pick the correct version based on the units of the constant
#7) normally we assume the solute is "non-volatile," think about what would happen if the solue was actually "volatile"
#8) approach this in terms of solids dissolving in liquids and gases dissolving in liquids
#9) the question is vague, considering we are discussing solutions right now approach in terms of what solutions do or do not conduct electricity
#10a) Hint Level 1write the reaction for the combustion of hydrocarbon CxHy and solve for moles of H2O and CO2
Hint Level 2 the moles of H2O is .500 and moles of CO2 is .500
Hint Level 3 think about how many moles of H would have been needed to make the moles of H2O and likewise how many moles of C would have been needed to make the moles of CO2
Hint Level 4 1.00mol H would have been needed and .500mol C would have been needed to make the H2O and CO2
#10b) Hint Level 1 figure out how many moles of O2 would have been needed to make the moles of H2O and CO2
Hint Level 2 add up the moles of O2 from the 1st hint, then convert to grams
#10c) Hint Level 1 solve for molality of the hydrocarbon
Hint Level 2 convert the grams of CCl4 into moles of hydrocarbon using the molality of the hydrocarbon
#10d) compare the "molecular weight" in #10c to the "empirical formula" weight in #10a
#14) Hess Law, to get deltaH of solution, write out the two formation reactions and figure out how they will add up to the "solution of LiF" reaction desired. To "comment on the relationship" think about the sign of deltaH and what role temperature would play in solubility
#15) for the three acids, whether it is strong or week will make a difference

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Chapter 11
Chapter 11 1st Year Review WS
#1) look in your notes from last year or the book
#2) both things have to do with collisions of reactant particles
#3) discuss what a catalyst does to the Ea and how it does it
#5, the second one) think about where the reactants and products would be relative to each other on the graph if a reaction does equilibrium

Page 311
#9a-d) the order of chemical A and B is given as the exponent, elements not listed have an order of zero
#11a-d) the units of k will always be nothing over Molarity(to the appropriate power) times the unit of time, or some appropriate version of that
#23a) although weird, it is possible to have an order that is a fraction
#26a) even though H+ is not written as a reactant in the overall equation it can still be part of what determines the rate.

Page 314
#33a) assume a month has 31 days
#43a) the A(knot) and A don't have to be in Molarity, atm is OK

Chapter 11 Worksheet #1
#1d) figure out which reactant is limiting then do a stoichiometry calculation to find the Molarity of C produced (note, you can use Molarity while doing the stoichiometry because the volume isn't changing)
#2c) Hint Level 1 your rate law in #2a should be 1st order based on chemical Y, so use the 1st order equation and the amount of chemical Y
Hint Level 2 the starting amount of Y is .60M and the ending amount of Y is the amount left after .20M Z is produced.
Hint Level 3 if .20M Z is produced then .20M Y must have reacted, so the ending amount of Y is .60M - .20M = .40M

Chapter 10 WS #2
#2b) Hint Level 1 for this one use the mole fraction of the solvent, not the one you used in 2a
Hint Level 2 don't forget that you need to multiply the moles of solute by its i value in the mole fraction of the solvent
#3) avogadro's number should be used at some point
#5) the author of this problem intentionally chose a couple of weird things that you are unlikely to know (formic acid and sodium formate). Don't look them up, use the data provided.

Chapter 11 Worksheet #2
#16.28) try starting with one of the steps as the slowest and see if the rate expression turns out like the question states

Page 311
#31a) make a quick graph of ln concentration versus time
#31b) find the slope of the line and make answer positive because rate constants are always positive
#31c) use the 1st order integrated rate law
#31d) use the rate expression assuming the reactant is 1st order

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Chapter 12
Chapter 12 1st year Review WS
#1) use an ICE chart
#2) Hint Level 1 ICE chart
Hint Level 2 note that Sulfur is a solid
Hint Level 3 40.0% of the .150M oxygen is the change in oxygen
#3) ICE chart
CPb) use the molarity from CPa1 as the initial SbCl5, then do an ICE chart, and use 29.2 percent of original SbCl5 as change in SbCl5

Page 344
#11) check that the equation is balanced (add missing chemicals if needed), include states (parenthesis mean gas, brackets mean aqueous)
#15) first figure out how to get the two reactions to add up to the other then adjust their K values accordingly
#17) write an equation for the 4th (written) reaction then figure out how to get the three reactions to add up to the 4th, then adjust their K values accordingly
#21b) the .159 grams and 313K are not used
#27a) the pressure of Cl2 must be zero, so the Q would be zero which is less than the K, so forward
#37a) Q is less than K so forward, then use x in an ICE chart
#41) Q is more than K so reverse, then use x in an ICE chart
#55) Hint Level 1 volume to grams, then grams to moles, then moles to pressure
Hint Level 2 then use x in ICE chart, then find pressure of isopropal alcohol remaining, then percent
Hint Level 3 you will need to use the quadratic formula for this one

Chapter 12 WS#3
#1) Hint Level 1 do a Q 1st and you should find the reaction is going backwards
Hint Level 2 because its going backwards, in the ICE chart, make the change of reactants positive and change of products negative
Hint Level 3 you'll need the quadratic equation for this one and the math is just messy, sorry
#2) When solving for Kp it must be done in atm
#3, 1st question) When solving for Kc it must be done in Molarity
#3, 3rd question) add the molarity of the "added" H2 and CO2 as mentioned in the 2nd question to your answers from the 1st question. This will give you the initial Molarities of H2 and CO2 in the ICE chart

Chapter 12 WS#4
#1968a) it doesn't say whether to solve for Kc or Kp. I solved for Kc so you need to first turn moles into Molarity
#1968b) Hint Level 1 solve for molarity of N2O4 then plug it into an ICE chart as the initial N2O4
Hint Level 2 the initial NO2 is zero
Hint Level 3 use an ICE chart and "x"
Hint Level 4 don't leave your answer in Molarity, turn it into moles
#1969a) Hint Level 1 write the reaction for the decomposition of water
Hint Level 2 the reaction is 2H2O(g) --> 2H2(g) + O2(g)
Hint Level 3then use the 1.00 atm and 1.00% decomposed to find the pressures of each chemical. An ICE chart will help.
#1969b) convert Kp into Kc then use the Molarities in the Kc expression
#1981a) Hint Level 1 notice the reaction has solid reactant and the two gas products are 1 to 1, based on this the total pressure must be from the two gas products only
Hint Level 2 because the gases are made at the same rate there pressure must be equal
#1981b) use 2x and x to represent the pressure of each gas
#1981c) Hint Level 1 based on 1981a each gas pressure will go down until it becomes .3295 atm, use this to figure out how much each gas has reacted
Hint Level 2 once you know the change in pressure of each gas (-.1705atm) you can solve for moles of each gas that reacted (use one of our old equation friends)
Hint Level 3 once you know the moles of each gas that reacted (6.97x10(-3)mol) you can find the moles of NH4HS solid that is made.
#4a) this is not an equilibrium question, it is old stuff
#4b) use the percent and the pressure from #a to figure out how much CO2 decomposed then plug it into an ICE chart
#4c) Hint Level 1 change moles of CO before reaction and at equilibrium to molarity then plug them into an ICE chart
Hint Level 2 use the equilibrium molarities of CO2 and CO, and the new given Kc to solve for the equilibrium molarity of O2
Hint Level 3 use the equilibrium molarity of O2 (.0520M) and the change in O2 from the ICE chart to find the initial O2 molarity
Hint Level 4 change molarity of O2 into moles

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Chapter 4.2 & 16
WS 1st Year Review
#1-3) do an ICE chart and plug in the molar solubility as the change in the solid
#4-6) do an ICE chart and plug in "x" as the change in the solid

Page 96 & 439
page 96 #7) use the solubility rules from lecture notes
page 439 #7) need to look up the Ksp values in the book

Page 439 (other one)
#9a & b) need to lookup ksp of BaF2 in chapter 16
#9b) solve for molarity of F- that is still dissolved after the ppt. then subtract that from the molarity of F- before the ppt. (this gives you the molarity of F- that precipitated)
#11) Hint Level 1 need to lookup ksp of CaSO4 in chapter 16
Hint Level 2 solve for the ion product
#13a) this has the weird diatomic ion Hg2(+2), so it stays together, don't split it into two mercury ions
#15) Hint Level 1 lead azide splits into Pb(+2) and 2 N3(-1) ions when it dissolves
Hint Level 2 convert the grams of lead azide to Molarity
Hint Level 3 the Molarity of lead is equal to the Molarity of lead azide are Molarity of azide is double the Molarity of lead azide
#17a) solve for molar solubility (x) then convert molarity into grams / liter

Page 440
#17b&c) solve for molar solubility (x) then convert molarity into grams / liter

WS 4.2 / 16 worksheet #2
#2) have to convert the solubility into Molarity then ICE chart
#10) the opposite of #2, when you solve for "x" it is in Molarity, so you then convert into grams / 100ml

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Chapter 13 & 14
Acid / Base 1st year Review WS
#13) Hint Level 1 you have to double the Ca(OH)2 molarity to get the OH- molarity
Hint Level 2 from the OH- molarity there are two possible routes, each with two steps (either OH- to H+ to pH, or OH- to pOH to pH)
#14) similar to #13 two possible routes, each with two steps
#15) what you write for reactants is based on whether it is strong or week
#16) use the titration equation
#17) get moles of OH- then that will equal moles of H+ . . .
#18b) rainwater is acidic because of CO2 in the air . . .
#19) the endpoint of the titration is in the middle of the vertical jump

Page 374
#25) show an H+ coming off
#35) Hint Level 1 write the equation and Ka expression
Hint Level 2 turn grams into moles then into molarity of weak acid
Hint Level 3 use the pH to get the H+ concentration and anion concentration
Hint Level 4 plug values into the Ka expression
#49) react with water
#67) Hint Level 1 write the equation and Kb expression (react with water)
Hint Level 2 use molarity and percent to get amount of base that reacted and amount of hydroxide and cation formed
Hint Level 3 plug values into an ICE chart then Kb expression
Page 396
#1 & 3) just like in lecture notes
Ch 13/14 WS #1A
#6-10) consider what the ions do in water to identify who is the acid and base and spectator ions, then just like lecture notes

Page 374 (more of it)
#55b) use Ka•Kb=1x10(-14) to get Kb of codeine
#55c) do ICE chart and use x for the OH- value, then convert OH- to pH
#57) Hint Level 1 turn pH into OH- concentration
Hint Level 2 write an equation for the weak base ammonia in water and the Kb expression
Hint Level 3 look up Kb of ammonia, use that and OH- concentration (which is also the NH4+ concentration) in the Kb expression to solve for NH3 concentration
Hint Level 4 turn molarity of NH3 into moles, then grams
#71a) No, Kw will be larger than what we are used to
#71b) Hint Level 1 you will need a new equation called the "van't Hoff equation"
Hint Level 2 there is a version of the equation in our book and a different version at the beginning of the ACS olympiad exam, use either one
Hint Level 3 using the new equation solve for the new Kw     

Worksheet #1B
#2) show FeCl3 dissolving in water, then add water (double the ligands), then show how it is acidic
#5a) add water to the methylamine
#5b) do an ICE chart with "x" as the hydroxide, solve for "x," then convert to pH
#7) get total moles of H+, then new molarity of H+, then pH
#8) Hint Level 1 figure out who wins between H+ and OH- (careful with calcium hydroxide)
Hint Level 2 get moles of which is left over (OH- in this case)
Hint Level 3 then molarity, then convert to pH
#9) BIG hint turn Ka into Kb because CN- is basic
Hint Level 1 get molarity of CN-
Hint Level 2 do an ICE chart with "x" as hydroxide
Hint Level 3 then convert to pH
#10) Hint Level 1 get moles of hydroxide
Hint Level 2 because it is a titration, moles acid = moles base (so now you know the moles H+)
Hint Level 3 grams over moles (no units because "molecular mass")

Worksheet #2
#2a) remember "mol acid = mol base" at the endpoint of titration
#2b) Hint Level 0 "ionization constant" means Ka of the acid
Hint Level 1 undo the pH into hydrogen ion molarity
Hint Level 2 get moles of OH- that reacted which is also moles of A- that was made
Hint Level 3 subtract moles of OH- from moles of HA in #1a to get moles of HA left at this point
Hint Level 4 turn moles of HA and A- into molarity
Hint Level 5 use the concentrations to solve for Ka
#2c) "base dissociation constant" means Kb. Remember there is a relationship between the Ka of a weak acid and the Kb of its conjugate base.
#2d) Hint Level 1 you know the moles of hydroxide that reacted in #1a, that will be equal to the moles of A- that was made
Hint Level 2 turn the moles of A- into molarity, then solve for OH-, etc.

Worksheet #3
#1b-e) be sure to account for the double hydroxides
#1d) don't forget to switch Ka into Kb
#2a) Nitrate is a spectator ion, so it is just the weak acid NH4(+)
#2g) Hint Level 1 make a data table of KOH added and pH to get started
Hint Level 2 your data table should be able to generate 5 points on the graph
Hint Level 3 even though the 5 points look like a smooth curve you should make a pH "jump" at the endpoint

Page 397 & 377 & 399
#9) need to lookup the Ka of lactic acid in book, page 382
#13) need to lookup the Ka of the acid HNO2 in the book, chapter 13 or appendix 1
#19a) need to lookup the Ka of the acid HC2H3O2 in the book, chapter 13 or appendix 1
#19b) the molarities both go down, but in the same proportion so the pH stays the same
#25a) need to lookup the Ka of the acid H2PO4(-1) in the book, chapter 13 or appendix 1
#25b) addition of H+ will consume weak base HPO4(-2) and produce weak acid H2PO4(-1)
#25c) addition of OH- will consume weak acid H2PO4(-1) and produce weak base HPO4(-2)
#31) Hint Level 1 if there is weak acid (HF) and its conjugate weak base (F-) it is a buffer
Hint Level 2 the important part of the starting chemical (SnF2) is that it gives off the weak base F-
Hint Level 3 the starting amount of F- is .0750 mol
page 377
#77) there are two ways to approach this, one is to calculate the Ka of each figure, the other is to look at the ratio of "split" species versus "joined" species
page 399
#55b) pKa = pH at the 1/2 way point of the titration, which is about a pH of 3.3

Worksheet #4
#1a) not a buffer, just the weak acetic acid
#1b) it is a buffer now
#1c) too much HCl was added, using up all of the weak base acetate. You need to figure out how much "extra" HCl was present after all the acetate is gone. H+ is based on that "extra" HCl.
#2a) Hint Level 1 this is not a buffer problem
Hint Level 2 the reaction is CO3(-2) + 2H+ --> CO2 + H2O
Hint Level 3 use PV=nRT to get moles of CO2, which equal moles of CO3(-2), which equal moles of K2CO3
Hint Level 4 percent problem using grams of K2CO3 and total grams of the dry mixture
#2b) Take a deep breath for this one. The HCl reacted with two of the solids, K2CO3 (making the CO2 as discussed in #2a) and KOH (a neutralization reaction). We need to find how much HCl was excess (didn't react) to find how much HCl did react with K2CO3 and KOH, then find how much HCl reacted with just the KOH which tells us how much KOH was present in the dry mixture.
Hint Level 1 get moles of OH- because it is the moles of excess HCl (answer is .130 mol)
Hint Level 2 subtract the excess HCl from the original amount given to get HCl that reacted (answer is .070 mol)
Hint Level 3 subtract the HCl that reacted with K2CO3 from the total HCl that reacted, to get HCl that reacted with KOH (answer is .050 mol), this equals the amount of KOH (.050 mol)
Hint Level 4 turn the moles of KOH into grams and solve for percent KOH, then solve for percent KCl (the only thing left)
#3a) not a buffer, just the weak acid (HOCl)
#3b) it is a buffer now
#3c) it's a trick, if the amount of HOCl made is .0040 M then the amount of HCl must also be .0040 M. pH is based on the HCl (the HOCl is weak and insignificant)
#4) Here we have the weak base OCl- being titrated with the strong acid HCl.
Before the titration it is just OCl- in water. During the titration it consumes OCl- and makes the weak acid HOCl.
At the endpoint the OCl- is gone and we have HOCl in water.

Ch 13/14 Practice Test
#1) consider the lab "molar mass of unknown acid"
#3) start with the [H+] of pure water and add the additional [H+] from the acid, then calc. pH
#4) each K represents each H+ coming off of the diprotic acid, and the overall reaction is the result of adding the individual reactions so combine the K values accordingly
#5a) just the weak acid
#5b) a buffer
#5c) still a buffer, but the addition of HCl has effected it
#6a) N•L = N•L
#6b) at equivalence point mol acid = mol base, then divide by the new volume
#6c) be sure to switch Ka into Kb
#7a) get mol of base, then mol base = mol acid, then molecular mass
#7b) get mol of NaOH which equals mol acid reacted, then subtract mol acid reacted from mol acid at start
#7c) undo the pH
#7d) using the pH=5.65 situation get Molarity of H+, A-, and HA then plug them into Ka expression
#8) NBA chart
#9a) old molarity stuff
#9b) dilution equation
#9c) get mol of HgO, then mol of OH- is double that, then mol acid = mol base, then molarity of HCl
#10a) pH converted to OH-
#10b) weak acid molarity will be the same as the OH-, and weak base molarity hasn't significantly changed, then plug into Kb expression

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Chapter 4.4 & 18
Redox Balancing WS
The following are the half reactions
#6) NO2-1 <----> NH3 and Al <----> Al(OH)4-1
#9) Zn <----> Zn(OH)4-2 and OH- <----> H2 .

Page 501
#11) Hint Level 1 Separate the oxidizing agents from the reducing agents to help organize
Hint Level 2 Cr+3 and Sn+2 can be both agents
Hint Level 3 Cr+3 can be reduced to either Cr+2 or Cr(s). It doesn't matter which you choose, we get the same ranking
Hint Level 4 The Cr+3 being oxidized is tough to find. It's lower on the chart and involves Cr2O7-2
Hint Level 5 The reducting agents (in no particular order) are Cr+3 and Hg and H2 and Sn+2 because they can be oxidized
The oxidizing agents (in no particular order) are Cr+3 and Sn+2 and Br2 because they can be reduced
#15c) Hint Level 1 It says "voltaic" so the final answer must be +
Hint Level 2 As the question is written both half equations as oxidation, so one of them must be flipped
#17All of them) Book doesn't say "voltaic" but it should so all answers must be +
#17c) Hint Level 1 There are two half equations in the chart with Iron(II) Hydroxide, you must choose the correct one
Hint Level 2 Remember you must have reduction and oxidation
Hint Level 3 Iron(II) Hydroxide must be a reactant in of the half equations, Oxygen must be a reactant in the other half equation
Hint Level 4 The 1st of the Iron(II) Hydroxide equations will not work, so you have to use the 3rd one down in the list
#19All of them) Again the book doesn't say "voltaic" but it should so all answers must be +
#72) Think about the electrolysis of water lab

Page 503
#61a) you don't need the voltage (it is for 61b), the half reaction is Pb(s) --> Pb+2(aq) + 2e-
#57a) not in water, so Al+3 can go to the cathode, the half reaction is 3e- + Al+3(aq) --> Al(s)
#57b) Hint Level 1 turn the mol e- from #57a into Coulombs
Hint Level 2 turn "a day" into seconds (assume 1 day = 24 hours)
Hint Level 3 use the Coulombs and seconds to get amps
#57c) Hint Level 1 the other half reaction is 2O-2(aq) --> O2(g) + 4e-
Hint Level 2 add the two half reactions together to get the overall reaction [note: 4Al+3(aq) and 6O-2(aq) is the same as 2Al2O3(aq)]
Hint Level 3 use the overall reaction to go from 10,000 g Al to mol O2
#59a) Hint Level 1 turn time into seconds (it will be 8700 seconds) then solve for Coulombs (it will be 17400 C)
Hint Level 2 take 82.0% of the Coulombs (it will be 14300 C)
Hint Level 3 the half reaction is e- + Ag+(aq) --> Ag(s)
Hint Level 4 turn the Coulombs into gram of Ag
#59b) (This is a wierd units question) d = m/v so m = v • d, and if you break apart the volume unit (cm cubed) into two pieces you get m = (cm squared times cm) • d. Plug in the grams and cm squared and density, then solve for cm.
#63) Hint Level 1 turn time into seconds then solve for Coulombs then solve for mol e-
Hint Level 2 the half reactions (unbalanced) are Cd(s) --> Cd(OH)2 + 2e- and 2e- + Ni2O3 --> 2Ni(OH)2
Hint Level 3 turn the mol e- into the grams of Cd and also into grams Ni2O3

Page 502
#34 and 38) Hint Level 1: to solve for K it means equilibrium so set E to zero and change Q into K
Hint Level 2: use Nernst equation to work bewteen E° and K, use deltaG° = - n F E° to work between deltaG° and E°
#53b) "unwrap" the pH to get the H+ concentration

Ch 18 WS Review #1
#3) see notes
#5) get Coulombs then convert to grams
#8) see notes about what happens when you try to reduce group I, II, & Al
#9) use Nernst even though it is only the reduction half
#10) get moles of NaI, which equal moles of I-, then get moles of Cr2O7-2, which equals moles of Na2Cr2O7, then get Liters then ml
#12) think about precipitate rules
#13) Hint Level 1 do two serperate problems (one acidic and one basic)
Hint Level 2 for each one half equation is Mn04-1 --> Mn+? and the other half equation is SO3-2 --> SO4-2
Hint Level 3 balance each situation and note the required charge on the Mn+?
#14b-d) bunch of Stoichiometry, etc.

Ch 18 WS Review #2A
#1a) use summation like we did a long time ago
#1b) get E° total then use the equation to go from E° to deltaG°
#1c) convert 1a's answer into kJ / K then use the "classic" thermodynamic equation
#3a) see notes about what happens when you try to reduce group I, II, & Al
#3b) look at the charge of Fe in both cases
#4a) write half equation to get moles of e- then do conversions
#4b) grams to Coulombs then solve for time

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Chapter 19 - 22
Page 605, 421, 548, 572
page 572 #23c) ammonia in water is always in equilibrium with ammonium hydroxide (which in water is NH4+1 and OH-) so in this case the addition to Al+3 would first react Al+3 with hydroxide to create the precipitate Aluminum Hydroxide. Then further addition would cause the ammonia to push out the hydroxide and create the complex ion.

525, 572, 548
page 525 #33a) look in the chapter for an example
#33b) you can solve this like the example in the book or use E=mc(2), if you use E=mc(2) put the mass defect in kilograms, and your answer comes out in Joules.

WS "Writing equation by type"
#5) nonmetal oxide and water make an acid
#6) metal oxide and water make a hydroxide
#7) metal and nonmetal make a salt
#8) organic addition reaction
#9) electrolysis (not in water)
#11) carbonates heated decompose into carbon dioxide and metallic oxide
#13) two reactions are happening (precipitate and acid/base)
#16) the excess chemical will be the ligand
#17) "equal amounts of equal molar" means only take the reaction 1 step forward
#19) elementary school volcano
#20) see reduction chart if needed

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