For the reaction, 2NO2(g) $\rightleftharpoons$ N2O4(g), when $\Delta$S = $-$176.0 JK$-$1 and $\Delta$H = $-$57.8 kJ mol$-$1, the magnitude of $\Delta$G at 298 K for the reaction is ___________ kJ mol$-$1. (Nearest integer)
Answer (integer)
5
Solution
Given, $\Delta$H = $-$ 57.8 kJ mol<sup>$-$1</sup><br/><br/>$\Delta$S = $-$ 176 JK<sup>$-$1</sup> mol<sup>$-$1</sup><br/><br/>T = 298 K<br/><br/>Using Gibb's free energy relation<br/><br/>$\Delta$G = $\Delta$H $-$ T$\Delta$S<br/><br/>where, $\Delta$G = change in Gibb's free energy<br/><br/>$\Delta$H = change in enthalpy<br/><br/>T = temperature<br/><br/>$\Delta$S = change in entropy<br/><br/>$\Delta$G = 57.8 kJ/mol $-$ [298 K $\times$ ($-$ 176 Jk<sup>$-$1</sup> mol<sup>$-$1</sup>)]<br/><br/>= 57.8 kJ/mol $-$ $\left( {298 \times {{ - 176} \over {1000}}kJ} \right)$ [$\therefore$ 1 kJ = 1000 J]<br/><br/>= $-$ 5.352 kJ/mol<br/><br/>| $\Delta$G | = 5.352<br/><br/>Hence, answer is 5.
About this question
Subject: Chemistry · Chapter: Thermodynamics · Topic: Zeroth and First Law
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