Question

For the reaction, $CaCO _{3( g )} \rightleftharpoons CaO _{( s )}+ CO _{2( g )}$ partial pressure of $CO _2$ at $1000 \,K$ is $0.003 \,atm . \Delta G^{\circ}=27.2 \,kcal$. Calculate the value of $\Delta G$.

• A. $12.6\, kcal$
• B. $15.6\, kcal$
• C. $13.4\, kcal$
• D. $14.2\, kcal$

Answer 1

Answer: (B)

$CaCO _{3( g )} \rightleftharpoons CaO _{( s )}+ CO _{2( g )}$
$K_p =p_CO_2 =0.003$ atm
$ΔG = ΔG^° + 2.303\,RT\, logK_p$
$= 27200 + 2.303 \times 2 \times 1000 \times log \,0.003$
$= 15.6\, kcal. (R = 2\, cal\, mol^{-1}\, K^{-1})$