Question

For the reaction, $N_{2}O_{4 \left(g\right)}\rightleftharpoons2\left(NO\right)_{2 \left(g\right)}\triangle U=2.1kCal,$ $\triangle S=20CalK^{- 1}$ $at300K$ , then $\triangle G$ is at $300K$ is...

• A. $+9.3kCal$
• B. $-9.3kCal$
• C. $-3.3kCal$
• D. $+3.3kCal$

Answer 1

Answer: (C)

$\triangle H=\triangle U+\triangle n_{g}RT$
$=2.1+\frac{1 \times 2 \times 300}{1000}$
$=2.1+0.6$
$=2.7KCal$
$\therefore \triangle G=\triangle H-T\triangle S$
$=2.7-\frac{300 \times 20}{1000}$
$=2.7-6$
$=-3.3KCal$