The decomposition equilibrium is endothermic

CHEMISTRY · Subjective · A Level · Chemistry · Gaseous equilibria (Kp) · Gaseous equilibria (Kp)

Problem

The decomposition equilibrium

2\,\mathrm{NOBr(g)} \rightleftharpoons 2\,\mathrm{NO(g)} + \mathrm{Br_2(g)}

is endothermic. At 350 K a mixture has

P_{\mathrm{NOBr}} = 1.20\,\text{atm}

P_{\mathrm{NO}} = 0.50\,\text{atm}

, and

P_{\mathrm{Br_2}} = 0.10\,\text{atm}

, values that satisfy

K_p(350\,\text{K}) = 1.7 \times 10^{-2}

. The temperature is then raised to 400 K, where

K_p(400\,\text{K}) = 5.0 \times 10^{-2}

. Immediately after the temperature change the partial pressures have not yet adjusted. Calculate the reaction quotient

Q_p

using the unchanged pressures and determine the direction of the net reaction as the system moves toward the new equilibrium at 400 K.