Question

Equilibrium constant $K_p$ for following reaction :
$ MgCO_3 \rightleftharpoons MgO(S) + CO_2 (g)$

• A. $ Kp = P_{CO_2}$
• B. $ Kp = P_{CO_2} \times \frac{P_{CO_2} \times P_{MgO}}{P_{MgCO_3}}$
• C. $ Kp = \frac{P_{CO_2} + P_{MgO}}{P_{MgCO_3}}$
• D. $ Kp = \frac{P_{MgCO_3}}{P_{CO_2} \times P_{MgO}}$

Answer 1

Answer: (A)

In heterogeneous system $K_c,K_p$ is not based upon concentratrion or pressure of solid substance. Hence, at equilibrium their concentration or pressure are assumed as one .
$\therefore \; MgCO_3(g) \rightleftharpoons MgO(s) + CO_2 (g) $
$K_p = P_{CO_2 }$