Thermochemistry BAT
AP Chemistry
Things that need to be in your HW folder when it’s turned in on test day…
This BAT sheet on another paper
Real AP worksheet
p204 #59-64
p204 #41,45,51,53,54
p206 #69-71,78
notes 5.3 & 5.4
p201 #6,37,39-41
notes 5.1 & 5.2
p201 #1,2,4,12,17,23
And for the test, you need to Be Able To…
…determine whether a process is exo- or endothermic and sketch an energy diagram to explain this…
1. In the combustion of glucose powder, C6H12O6, 2538.9 kJ of heat are released for every mole of
glucose consumed.
a) Write the balanced reaction for this if only gases are produced.
b) Sketch an energy diagram to show the initial and final energy levels for the reaction –
include some indication of activation energy in your diagram
c) Place the indicated quantity of heat on the correct side of the equation – as reactant or
product
d) Which is more likely to be thermodynamically favored – the forward or reverse reaction?
e) Is this reaction exothermic or endothermic? If the reverse reaction were feasible, would this
be exo- or endothermic?
f) If liquid water is instead produced, how would the magnitude and sign of ΔH change?
g) Include the situation described in part f) in your energy diagram.
h) Determine how many kilojoules of energy are released for every gram of glucose.
…manipulate the energy released or consumed in a reaction as necessary…
2. Write the reaction for the thermal decomposition of calcium carbonate. (Check yourself because it
balances without coefficients.)
3. Use the reaction from problem 2 and the information that it requires the addition of 178.1 kJ to
make the reaction proceed to answer these questions…
a) How many kJ of heat are absorbed per gram of calcium carbonate consumed?
b) How much heat would be needed to produce 4.56 mol of CO2?
c) Is this equation exothermic or endothermic?
d) How much heat is needed to decompose 56.5 g of calcium carbonate?
…calculate calorimetry info…
4. The specific heat of aluminum is 0.90 J g-1 K-1 and iron is 0.45 J g-1 K-1. How much hotter would a
150-g sample of iron be than a sample of aluminum with the same mass would be if 134 J were
added to each?
5. How much heat is needed to heat a 0.45 kg puddle of mercury (specific heat 0.14 J g-1 K-1) from
22.5 °C to 65.7 °C?
6. What is the specific heat of a substance that takes 10.499 kJ to raise its temperature 18.2 °C if the
substance has a mass of 0.437 kg?
7. In a calorimeter, 50 mL of 1 M NaOH is added to 50 mL of 1 M HCl. The temperature of the
solution (assuming a specific heat and density equal to that of pure water) rises 4.5 °C.
a) Determine how many moles of each reactant react.
b) Write the balanced reaction and net ionic equation for the reaction
c) Determine the energy released by the reaction as described in the beginning of this
problem.
d) Determine the amount of heat released per mole of water formed.
e) Determine the amount of heat released per gram of water formed.
…use Hess’s Law to determine the enthalpy change of a reaction even if heats of formation are
unknown…
8. From the first three enthalpies of reaction, determine the ΔH for the fourth reaction.
H2 (g) + F2 (g) → 2 HF (g)
C (s) + 2 F2 (g) → CF4 (g)
2 C (s) + 2 H2 (g) → C2H4 (g)
C2H4 (g) + 6 F2 (g) → 2 CF4 (g) + 4 HF (g)
ΔH = -537 kJ
ΔH = -680 kJ
ΔH = + 52.3 kJ
ΔH = ???
…use enthalpies of formation (as found in appendix C of your book) to determine the enthalpy change in
a reaction…
9. Check the two enthalpies of reaction as given in problems 1 and 8 using appendix C.
10. Calculate the standard enthalpy change for the reaction of iron (II) oxide and oxygen gas to
produce iron (III) oxide.
11. Calculate how much energy is released from the complete combustion of liquid methanol (CH3OH)
to gaseous products.
12. The heat of combustion of fructose (also C6H12O6) is –2812 kJ mol-1 if gaseous products are
produced. What is the heat of formation for fructose in kJ mol-1?
…write net ionic equations involving precipitates, gas formers, strong/weak acids, and all soluble
products…
13. Write and balance the following reactions. All reactants are aqueous unless specifically written
otherwise.
a) copper (II) nitrate poured into sodium hydroxide producing a precipitate
b) lithium bicarbonate solution added to nitric acid producing a gas
c) acetic acid mixed with ammonium chlorate producing no precipitate or gas
d) sulfuric acid and barium hydroxide mixed producing no precipitate or gas
e) barium perchlorate mixed with cesium nitrate producing no precipitate or gas
f) copper (II) chloride mixed with solid potassium
g) hydrobromic acid having chlorine gas bubbled in
14. What are the only two categories of chemicals that should be broken into ions?
15. Write net ionic reactions for all the reactions in #13.