If three moles of an ideal gas at 300 K expand isotherrnally from 30 dm 3 to 45 dm 3 against a constant opposing pressure of 80 kPa , then the amount of heat transferred is J.

Chemistry · Thermodynamics & Thermochemistry

JEE Main 2024 — 27 January, Shift 1 — Question 76

If three moles of an ideal gas at 300 K expand isotherrnally from $30 \mathrm{dm}^{3}$ to $45 \mathrm{dm}^{3}$ against a constant opposing pressure of 80 kPa , then the amount of heat transferred is $\qquad$ J.

Answer: 1200

Numerical answer — enter this value.

Step-by-step solution

Using, first law of thermodynamics,

$\Delta \mathrm{U}=\mathrm{Q}+\mathrm{W}$

$\Delta \mathrm{U}=0$ : Process is isothermal

$\mathrm{Q}=-\mathrm{W}$

$\mathrm{W}=-\mathrm{P}_{\mathrm{ext}} \Delta \mathrm{V}:$ Irreversible

$=-80 \times 10^{3}(45-30) \times 10^{-3}$

$=-1200 \mathrm{~J}$

Answer key and solution verified before publishing.

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Exam: JEE Main 2024
Paper: 27 January, Shift 1
Subject: Chemistry
Chapter: Thermodynamics & Thermochemistry
Topic: Internal Energy and the First Law