7.3 Equilibrium calculations  (Page 9/11)

A student solved the following problem and found the equilibrium concentrations to be [SO ₂ ] = 0.590 M , [O ₂ ] = 0.0450 M , and [SO ₃ ] = 0.260 M . How could this student check the work without reworking the problem? The problem was: For the following reaction at 600 °C:

$2{\text{SO}}_2(g)+{\text{O}}_2(g)\rightleftharpoons 2{\text{SO}}_3(g)K_c=4.32$

What are the equilibrium concentrations of all species in a mixture that was prepared with [SO ₃ ] = 0.500 M , [SO ₂ ] = 0 M , and [O ₂ ] = 0.350 M ?

A student solved the following problem and found [N ₂ O ₄ ] = 0.16 M at equilibrium. How could this student recognize that the answer was wrong without reworking the problem? The problem was: What is the equilibrium concentration of N ₂ O ₄ in a mixture formed from a sample of NO ₂ with a concentration of 0.10 M ?

$2{\text{NO}}_2(g)\rightleftharpoons {\text{N}}_2{\text{O}}_4(g)K_c=160$

Assume that the change in concentration of N ₂ O ₄ is small enough to be neglected in the following problem.

(a) Calculate the equilibrium concentration of both species in 1.00 L of a solution prepared from 0.129 mol of N ₂ O ₄ with chloroform as the solvent.

${\text{N}}_2{\text{O}}_4(g)\rightleftharpoons 2{\text{NO}}_2(g)K_c=1.07\times {10}^{\mathrm{-5}}$ in chloroform

(b) Show that the change is small enough to be neglected.

Assume that the change in concentration of COCl ₂ is small enough to be neglected in the following problem.

(a) Calculate the equilibrium concentration of all species in an equilibrium mixture that results from the decomposition of COCl ₂ with an initial concentration of 0.3166 M .

${\text{COCl}}_2(g)\rightleftharpoons \text{CO}(g)+{\text{Cl}}_2(g)K_c=2.2\times {10}^{\mathrm{-10}}$

(b) Show that the change is small enough to be neglected.

Assume that the change in pressure of H ₂ S is small enough to be neglected in the following problem.

(a) Calculate the equilibrium pressures of all species in an equilibrium mixture that results from the decomposition of H ₂ S with an initial pressure of 0.824 atm.

$2{\text{H}}_2\text{S}(g)\rightleftharpoons 2{\text{H}}_2(g)+{\text{S}}_2(g)K_P=2.2\times {10}^{\mathrm{-6}}$

(b) Show that the change is small enough to be neglected.

What are all concentrations after a mixture that contains [H ₂ O] = 1.00 M and [Cl ₂ O] = 1.00 M comes to equilibrium at 25 °C?

${\text{H}}_2\text{O}(g)+{\text{Cl}}_2\text{O}(g)\rightleftharpoons 2\text{HOCl}(g)K_c=0.0900$

What are the concentrations of PCl ₅ , PCl ₃ , and Cl ₂ in an equilibrium mixture produced by the decomposition of a sample of pure PCl ₅ with [PCl ₅ ] = 2.00 M ?

${\text{PCl}}_5(g)\rightleftharpoons {\text{PCl}}_3(g)+{\text{Cl}}_2(g)K_c=0.0211$

Calculate the pressures of all species at equilibrium in a mixture of NOCl, NO, and Cl ₂ produced when a sample of NOCl with a pressure of 10.0 atm comes to equilibrium according to this reaction:
$\text{2NOCl}(g)\rightleftharpoons \text{2NO}(g)+{\text{Cl}}_2(g)K_P=4.0\times {10}^{\text{−4}}$