Enthalpy Stoichiometry Worksheet

Enthalpy Stoichiometry

Read each question carefully and answer to the best of your ability. Show all your work for calculations.

1. Which of the following best describes an endothermic reaction?

2. What is the standard enthalpy of formation (ΔH°f) for an element in its most stable state?

3. The energy required to break bonds is  , while the energy released when forming bonds is  .

4. Hess's Law states that the total enthalpy change for a reaction is the sum of the enthalpy changes for the individual  .

5. Explain the difference between enthalpy and entropy.

6. A positive ΔH value indicates an exothermic reaction.

7. The enthalpy of formation of H₂O(l) is the same as H₂O(g).

8. Given the following reactions:

C(s) + O₂(g) → CO₂(g) ΔH = -393.5 kJ/mol

H₂(g) + ½ O₂(g) → H₂O(l) ΔH = -285.8 kJ/mol

CH₄(g) + 2O₂(g) → CO₂(g) + 2H₂O(l) ΔH = -890.3 kJ/mol

Calculate the enthalpy change for the reaction: C(s) + 2H₂(g) → CH₄(g)

9. A student performs an experiment to determine the heat of neutralization of a strong acid with a strong base using a calorimeter. The initial temperature of the solution was 22.5 °C and the final temperature after mixing was 29.8 °C. If the total volume of the solution was 100 mL and assuming the density and specific heat capacity are the same as water (1 g/mL and 4.18 J/g°C), calculate the heat absorbed by the solution.