A rigid vessel at is charged with of dinitrogen tetroxide gas, N O (g)

CHEMISTRY · Multi-part · A Level · Chemistry · Gaseous equilibria (Kp) · Gaseous equilibria (Kp)

Problem

A rigid

10.0\,\text{L}

vessel at

298\,\text{K}

is charged with

0.0800\,\text{mol}

of dinitrogen tetroxide gas, N

_2

_4

(g). The gas partially dissociates according to the equilibrium reaction

\mathrm{N_2O_4(g)} \rightleftharpoons 2\,\mathrm{NO_2(g)}.

After equilibrium is established at

298\,\text{K}

, the total pressure in the vessel is measured to be

0.724\,\text{atm}

, and the equilibrium partial pressure of NO

_2

is found to be

0.561\,\text{atm}

. Use

R = 0.08206\,\text{L atm mol}^{-1}\,\text{K}^{-1}

. (a) Determine the equilibrium partial pressure of N

_2

_4

(g) in the vessel. (b) Calculate the numerical value of the equilibrium constant,

K

, for the dissociation reaction at

298\,\text{K}

. (c) Using your value of

K

, compute the standard Gibbs free energy change,

\Delta G^\circ

, for the reaction at

298\,\text{K}

\text{kJ mol}^{-1}

. (d) Discuss whether the dissociation of N

_2

_4

to NO

_2

is thermodynamically favorable under standard-state conditions, and compare this conclusion with the observed equilibrium composition in the vessel.