Enthalpy Concepts Worksheet

Enthalpy Concepts Worksheet

Read each question carefully and provide your best answer. Show all your work for calculations.

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

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

1. Enthalpy is a state function, meaning its value depends only on the initial and final states of the system.

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

1. The change in enthalpy for a reaction is represented by the symbol  .

2. 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.

1. Explain the difference between enthalpy and internal energy.

2. Describe how calorimetry is used to measure enthalpy changes.

3. Given the following reactions:

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

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

C₂H₂(g) + ⁵/₂O₂(g) → 2CO₂(g) + H₂O(l) ΔH = -1300 kJ/mol

Calculate the enthalpy change for the reaction: 2C(s) + H₂(g) → C₂H₂(g)