Question

For the reaction given below the values of standard Gibbs free energy of formation at 298 K are given.
What is the nature of the reaction?
$I_2+H_{2}S\to 2HI+S$
$\Delta G_f^0\left(HI\right)=1.8kJmo{l}^{-1}$, $\Delta G_f^0\left(H_{2}S\right)=33.8kJmo{l}^{-1}$

• A. Non-spontaneous in forward direction
• B. Spontaneous in forward direction
• C. Spontaneous in backward direction
• D. Non-spontaneous in both forward and backward directions

Answer 1

Answer: (B)

Spontaneous in forward direction

$I_2+H_{2}S\to 2HI+S$
$\Delta G^0=\sum G_{f\left(products\right)}^0-\sum G_{f\left(Reactants\right)}^0$ = -30.2 kJ
Hence, the reaction is spontaneous in forward direction.