High School

For a certain reaction at constant pressure in Chemistry, ΔH = 215 kJ, and 22 kJ of expansion work is done on the system by compressing it into a smaller volume. What is ΔU for this process?

A) 193 kJ
B) 193 kJ
C) 237 kJ
D) 237 kJ

Answer :

Final answer:

The change in internal energy (ΔU) for the reaction is calculated using the enthalpy change (ΔH) and the work done on the system, resulting in ΔU being 237 kJ.

Explanation:

To calculate the change in internal energy (ΔU) for the chemical reaction provided, we need to apply the first law of thermodynamics which states that ΔU = q + w, where q stands for the heat exchange with the surroundings and w stands for the work done on or by the system.

In the question, we're given the enthalpy change (ΔH = 215 kJ) and the work done on the system by compression (22 kJ). Since the work is done on the system, it will be a positive value when calculating ΔU. Therefore, ΔU = ΔH + w = 215 kJ + 22 kJ = 237 kJ. Thus, the correct answer is (c) 237 kJ.