The heat of solution of anhydrous CuSO 4 and CuSO 4 × 5 H 2 O are -70 kJ mol -1 and +12 kJ mol -1 respectively. The heat of hydration of CuSO 4 to CuSO 4 × 5 H 2 O is -x kJ . The value of x is .

Chemistry · Thermodynamics & Thermochemistry

JEE Main 2024 — 9 April, Shift 1 — Question 76

The heat of solution of anhydrous $\mathrm{CuSO}_{4}$ and $\mathrm{CuSO}_{4} \cdot 5 \mathrm{H}_{2} \mathrm{O}$ are $-70 \mathrm{~kJ} \mathrm{~mol}^{-1}$ and $+12 \mathrm{~kJ} \mathrm{~mol}^{-1}$ respectively.

The heat of hydration of $\mathrm{CuSO}_{4}$ to $\mathrm{CuSO}_{4} \cdot 5 \mathrm{H}_{2} \mathrm{O}$ is $-x \mathrm{~kJ}$ . The value of $x$ is $\qquad$ .

Answer: 82

Numerical answer — enter this value.

Step-by-step solution

(1) $\mathrm{CuSO}_{4}(\mathrm{~s})+5 \mathrm{H}_{2} \mathrm{O} \xrightarrow{\mathrm{x}} \mathrm{CuSO}_{4} \cdot 5 \mathrm{H}_{2} \mathrm{O}$

(2) $\mathrm{CuSO}_{4} .5 \mathrm{H}_{2} \mathrm{O}+\mathrm{H}_{2} \mathrm{O} \xrightarrow{12} \mathrm{CuSO}_{4}$ (aq) $\mathrm{CuSO}_{4}+\mathrm{H}_{2} \mathrm{O} \xrightarrow{-70} \mathrm{CuSO}_{4}(\mathrm{aq})$

from (1) & (2)

$-70=\mathrm{x}+12$

$\mathrm{x}=-82$

Answer key and solution verified before publishing.

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Exam: JEE Main 2024
Paper: 9 April, Shift 1
Subject: Chemistry
Chapter: Thermodynamics & Thermochemistry
Topic: Thermochemistry and Enthalpy Changes