Question

The following reaction is performed at 298 K.
$2NO\left(g\right)+O_2\rightleftharpoons 2N{O}_2\left(g\right)$
The standard free energy of formation of NO(g) is 86.6 kJ/mol at 298 K. What is the standard free energy of formation of $N{O}_2\left(g\right)at298K?(K_p=1.6\times {10}^{12})$

• A. $R\left(298\right)ln(1.6\times {10}^{12})-86600$
• B. 86600 + R(298) ln(1.6 $\times {10}^{12}$)
• C. 866600 - $\frac{ln(1.6\times {10}^{12})}{R\left(298\right)}$
• D. $0.5[2\times 86600-R(298\left)ln\right(1.6\times {10}^{12}\left)\right]$

Answer 1

The correct option is D $0.5[2\times 86600-R(298\left)ln\right(1.6\times {10}^{12}\left)\right]$

$△G_{R{x}^n}=2△G_{N{O}_2}-2△G_{NO}$
$△G_{N{O}_2}=△G_{NO}+\frac{1}{2}△G_{Rx}$
$=△G_{NO}+\frac{1}{2}(-RTl{n}_e{K}_p)$
$=0.5[2\times 86000-R(298\left)l{n}_e\right(1.6\times {10}^{12}\left)\right]$