Enthalpy of Formation Worksheet

Enthalpy of Formation Worksheet

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

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

2. Which of the following statements is true regarding an exothermic reaction?

3. The enthalpy change that occurs when one mole of a compound is formed from its constituent elements in their standard states is called the standard enthalpy of  .

4. Hess's Law states that if a reaction can be expressed as a series of steps, then the enthalpy change for the overall reaction is the   of the enthalpy changes for the individual steps.

5. The standard enthalpy of formation of H₂(g) is 0 kJ/mol.

6. An endothermic reaction feels cold to the touch because it releases heat to the surroundings.

7. Define standard enthalpy of formation. Why is it useful in chemistry?

8. Given the following standard enthalpies of formation:

ΔH°f [CO₂(g)] = -393.5 kJ/mol

ΔH°f [H₂O(l)] = -285.8 kJ/mol

ΔH°f [CH₄(g)] = -74.8 kJ/mol

Calculate the enthalpy change for the combustion of methane (CH₄):

CH₄(g) + 2O₂(g) → CO₂(g) + 2H₂O(l)