Question

At 320 K, a gas A2 is 20% dissociated to A(g). The standard free energy change at 320 K and 1 atm in J mol$^{-1}$ is approximately : (R=8.314 JK$^{-1}$ mol$^{-1}$; ln 2=0.693; ln 3=1.098)

• A. 4763
• B. 2068
• C. 1844
• D. 4281

Answer 1

Answer: (D)

4281

Answer 2

${A2(g)<=>2A(g)}$
1 0
$1-1\times\frac{20}{100} 2\times\frac{20}{100}$
$0.8 \,0.4$
$K_{p}=\frac{\left(p_{A}\right)^{2}}{\left(p_{A_2}\right)}=\frac{0.4\times0.4}{0.8}=0.2$
$\Delta G^{\circ}=$ -2.303 ? 8.314 ? 320 log 0.2 = 4281 J/mole