13.4 Equilibrium calculations  (Page 7/11)

A reaction is represented by this equation: $\text{A}(aq)+2\text{B}(aq)\rightleftharpoons 2\text{C}(aq)K_c=1\times {10}^3$

(a) Write the mathematical expression for the equilibrium constant.

(b) Using concentrations ≤1 M , make up two sets of concentrations that describe a mixture of A, B, and C at equilibrium.

A reaction is represented by this equation: $2\text{W}(aq)\rightleftharpoons \text{X}(aq)+2\text{Y}(aq)K_c=5\times {10}^{\mathrm{-4}}$

(a) Write the mathematical expression for the equilibrium constant.

(b) Using concentrations of ≤1 M , make up two sets of concentrations that describe a mixture of W, X, and Y at equilibrium.

What is the value of the equilibrium constant at 500 °C for the formation of NH ₃ according to the following equation?

${\text{N}}_2(g)+3{\text{H}}_2(g)\rightleftharpoons 2{\text{NH}}_3(g)$

An equilibrium mixture of NH ₃ ( g ), H ₂ ( g ), and N ₂ ( g ) at 500 °C was found to contain 1.35 M H ₂ , 1.15 M N ₂ , and 4.12 $\times$ 10 ⁻¹ M NH ₃ .

Hydrogen is prepared commercially by the reaction of methane and water vapor at elevated temperatures.

${\text{CH}}_4(g)+{\text{H}}_2\text{O}(g)\rightleftharpoons 3{\text{H}}_2(g)+\text{CO}(g)$

What is the equilibrium constant for the reaction if a mixture at equilibrium contains gases with the following concentrations: CH ₄ , 0.126 M ; H ₂ O, 0.242 M ; CO, 0.126 M ; H ₂ 1.15 M , at a temperature of 760 °C?

A 0.72-mol sample of PCl ₅ is put into a 1.00-L vessel and heated. At equilibrium, the vessel contains 0.40 mol of PCl ₃ ( g ) and 0.40 mol of Cl ₂ ( g ). Calculate the value of the equilibrium constant for the decomposition of PCl ₅ to PCl ₃ and Cl ₂ at this temperature.

At 1 atm and 25 °C, NO ₂ with an initial concentration of 1.00 M is 3.3 $\times$ 10 ⁻³ % decomposed into NO and O ₂ . Calculate the value of the equilibrium constant for the reaction.

$2{\text{NO}}_2(g)\rightleftharpoons 2\text{NO}(g)+{\text{O}}_2(g)$

Calculate the value of the equilibrium constant K _P for the reaction $2\text{NO}(g)+{\text{Cl}}_2(g)\rightleftharpoons 2\text{NOCl}(g)$ from these equilibrium pressures: NO, 0.050 atm; Cl ₂ , 0.30 atm; NOCl, 1.2 atm.

When heated, iodine vapor dissociates according to this equation:

${\text{I}}_2(g)\rightleftharpoons 2\text{I}(g)$

At 1274 K, a sample exhibits a partial pressure of I ₂ of 0.1122 atm and a partial pressure due to I atoms of 0.1378 atm. Determine the value of the equilibrium constant, K _P , for the decomposition at 1274 K.

A sample of ammonium chloride was heated in a closed container.

${\text{NH}}_4\text{Cl}(s)\rightleftharpoons {\text{NH}}_3(g)+\text{HCl}(g)$

At equilibrium, the pressure of NH ₃ ( g ) was found to be 1.75 atm. What is the value of the equilibrium constant K _P for the decomposition at this temperature?