Question

The values of $\Delta H$ and $\Delta S$ for the reaction, C(graphite) + $C{O}_2\left(g\right)\to 2CO\left(g\right)$ are 170 kJ and $170J{K}^{-1}$ respectively. This reaction will be spontaneous at:

• A. 510 K
• B. 710 K
• C. 910 K
• D. 1010 K

Answer 1

Answer: (D)

1010 K

For a spontaneous reaction, $△G=$ Negative

And at equilibrium $△G=0$ i.e $△H=T△S$

$\Rightarrow T=\frac{170\times {10}^3}{170}$

$\Rightarrow T=1000K$

Therefore, at this temperature, reaction is at equilibrium i.e $△G=0$ and above this temperature $△G$ will be negative and reaction will be spontaneous.