Thermochemistry Practice Problems
1. A 1.000 g sample of octane (C8H18) is burned in a bomb calorimeter containing 1200
grams of water at an initial temperature of 25.00ºC. After the reaction, the final
temperature of the water is 33.20ºC. The heat capacity of the calorimeter (also known as
the “calorimeter constant”) is 837 J/ºC. The specific heat of water is 4.184 J/g ºC.
Calculate the heat of combustion of octane in kJ/mol
2. You place 300.0 g of water in a coffee-cup calorimeter and the temperature of the water
is 22.3C. A 94.5 g piece of silver metal is heated to 100.0C and added to the water in
the calorimeter. What will the final temperature of the silver and the water be? The
specific heat of silver is 0.235 J/gC and the specific heat of water is 4.184 J/gC.
ACADEMIC ACHIEVEMENT CENTER
Advancing Students… Enhancing Learning
[email protected] ǀ 410-704-2291
3. Find the ΔH for the reaction below, given the following reactions and subsequent ΔH
values:
N2H4 (l) + CH4O(l) → CH2O(g) + N2 (g) + 3H2 (g)
2NH3 (g) → N2H4 (l) + H2 (g) ΔH = 22.5 kJ
2NH3 (g) → N2 (g) + 3H2(g) ΔH = 57.5 kJ
CH2O(g) + H2 (g) → CH4O(l) ΔH = 81.2 kJ
4. Given the following bond dissociation energies (H-C is 413 kJ/mol; H-H is 436 kJ/mol;
C=C is 614 kJ/mol; C-C is 348 kJ/mol), determine ΔH for the reaction:
H2C=CH2(g) + H2(g) --> H3C-CH3(g)
ACADEMIC ACHIEVEMENT CENTER
Advancing Students… Enhancing Learning
[email protected] ǀ 410-704-2291
5. Calculate the work done when 63.0 g of tin are dissolved in excess acid at 1.00 atm and
25°C
Sn (s) + 2H+ (aq)  Sn2+ (aq) + H2 (g)
ACADEMIC ACHIEVEMENT CENTER
Advancing Students… Enhancing Learning
[email protected] ǀ 410-704-2291
1.
2.
3.
4.
5.
-5472 kJ/mol
23.7 °C
-46.5 kJ
124 kJ
-1.314 kJ
ACADEMIC ACHIEVEMENT CENTER
Advancing Students… Enhancing Learning
[email protected] ǀ 410-704-2291