The industrial synthesis of ammonia is represented by the balanced equation

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

Problem

N_2(g) + 3\,H_2(g) \rightleftharpoons 2\,NH_3(g)

. For this reaction,

K_p = 6.0 \times 10^{-3}

400\,\text{K}

. A rigid

10.0\,\text{L}

vessel at

400\,\text{K}

contains the following initial partial pressures:

P(N_2) = 5.00\,\text{atm}

P(H_2) = 9.00\,\text{atm}

, and

P(NH_3) = 0.00\,\text{atm}

. (a) Using the ideal‐gas law, convert each initial partial pressure to an initial molar concentration (

\text{mol}\,\text{L}^{-1}

). (b) Derive an expression that relates

K_p

K_c

for this reaction at

400\,\text{K}

, and calculate the numerical value of

K_c

. (c) Define a single algebraic symbol to represent the change in concentration as the system proceeds toward equilibrium, and express the equilibrium concentration of each species in terms of that symbol. (d) Formulate and solve the equation that results when the expressions from part (c) are substituted into the equilibrium‐constant expression

K_c

. Determine the equilibrium molar concentration of each species.

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