Question

For a reaction, $P + Q \to R + S$. The value of $\Delta H^°$ is $-30\, kJ\, mol^{-1}$ and $\Delta S$ is $-100\, J\, K^{-1}\, mol^{-1}$. At what temperature the reaction will be at equilibrium?

• A. $27\,{}^°C$
• B. $52\,{}^°C$
• C. $30\,{}^°C$
• D. $45\,{}^°C$

Answer 1

Answer: (A)

$\Delta G = \Delta H - T\Delta S$,
At equilibrium, $\Delta G = 0$, $\Delta H = T\Delta S$
$30000 = T \times 100$
$T = 300 \,K$ or $27\,{}^°C$