Question

For the reaction ${\text{H}}_{\text{2}}\text{(g) +}{\text{I}}_{\text{2}}\text{(g)}\rightleftharpoons \text{2HI(g)}$
$K_c=66.9$ at ${350}^{\circ }$C and $K_c=50.0$ at ${448}^{\circ }$C. The reaction has:

• A. $\Delta H=+ve$
• B. $\Delta H=-ve$
• C. $\Delta H=Zero$
• D. $\Delta H=$ Not found the signs

Answer 1

Answer: (B)

$\Delta H=-ve$

As temp. increases, eqm constant value decreases so its an exothermic reaction and $\Delta H=-ve$. (Refer table)
Hence, the correct option is B