Thermochemistry Practice Test

1. What is the heat capacity of gold if it requires 48.8 J to raise the temperature of 15.0 grams of gold by 25°C.

2. The heat of formation of Fe₂O₃ (s) is - 826 kJ/mol. Calculate the heat released by the reaction of 4 Fe (s) + 3 O₂ (g) --> 2 Fe₂O₃ (s) when 55.8 g sample of iron is reacted.

3. Calculate ÆH° for the reaction
C₂H₄ (g) + 2 H₂ (g) --> C₄H₈ (g)
using the following data:

Cmpd. ÆH° combustion
C₄H₈ (g) - 2341 kJ/mol
H₂ (g) - 286 kJ/mol
C₄H₈ (g) - 2755 kJ/mol

4. The combustion of methanol takes place according to the reaction:

2 CH₃OH (l) + 3 O₂ (g) --> 2 CO₂ (g) + 4 H₂O (l)
Compute ÆH° for the combustion of one mole of methanol given the following heats of formation:
Cmpd. ÆHf°
CH₃OH (l) - 238.5 kJ/mol
CO₂ (g) - 393.5 kJ/mol
H₂O (l) - 285.6 kJ/mol

5. Using the bond dissociation energies listed below, calculate H° for the reaction:

C₂H₄ + Cl₂ ---> C₂H₄Cl₂

Cl -Cl 243 kJ/mol; C-C 350 kJ/mol; C=C 611 kJ/mol; C-CL 330 kJ/mol; C-H 410 kJ/mol;

6. A 20 g piece of aluminum, at a temperature of 100°C, is placed in a coffee cup calorimeter which contains 100 mL of water at 20.0°C. Aluminum has a heat capacity of 0.902 J/g°C. After the water and the aluminum come to thermal equilibrium, what is the temperature of the water?

7. Calculate the kinetic energy of a 50 g weight which is traveling at 50 m/s