Chemistry · Thermodynamics & Thermochemistry

NEET (UG) 2023 — Question 71

Which amongst the following options is the correct relation between change in enthalpy and change in internal energy?

Option A:
$\Delta \mathrm{H}=\Delta \mathrm{U}+\Delta \mathrm{n}_{\mathrm{g}} \mathrm{RT}$
Correct
Option B:
$\Delta \mathrm{H}-\Delta \mathrm{U}=-\Delta \mathrm{nRT}$
Option C:
$\Delta \mathrm{H}+\Delta \mathrm{U}=\Delta \mathrm{nR}$
Option D:
$\Delta \mathrm{H}=\Delta \mathrm{U}-\Delta \mathrm{n}_{\mathrm{g}} \mathrm{RT}$

Answer: A

Step-by-step solution

From definition, enthalpy $H = U + PV$ . For a reaction at constant pressure, $\Delta H = \Delta U + P\Delta V$ . For ideal gases, $P\Delta V = \Delta n_g RT$ , where $\Delta n_g$ is the change in moles of gas. Thus, $\Delta H = \Delta U + \Delta n_g RT$ . Therefore, option A is correct.

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Exam: NEET (UG) 2023
Paper: 2023 paper
Subject: Chemistry
Chapter: Thermodynamics & Thermochemistry
Topic: Introduction to Terminology in Thermodynamics

Answer: A

Step-by-step solution

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