Equilibrium Calculations

When 0.40 mole of SO₂ and 0.60 mole of O₂ are placed in an evacuated 1.00–liter flask, the reaction represented below occurs.

2SO_{2 (g)} + O_{2 (g)} ↔ 2SO_{3 (g)}

After the reactants and the product reach equilibrium and the initial temperature is restored, the flask is found to contain 0.30 mole of SO₃. Based on these results, the equilibrium constant, Kc, for the reaction is

• 20

• 10

• 6.7

• 2.0

H_2(g) +I_2(g) ↔ 2HI_(g)

All gases begin with an initial concentration of 2.0 M. Equilibrium is established, and the concentration of HI is known to be 4.8 M. What is the value of the equilibrium constant?

• 1.2

• 2.4

• 32

• 64

0.600 moles of NO and 0.750 moles of O₂ are placed in an empty 2.00 L flask. The system is allowed to establish equilibrium. What will be the equilibrium concentration of each species in the flask?

2 NO(g) + O₂(g) ↔ 2 NO₂(g)

Kc = 5.00 x 10^-6

use 5% rule

• [NO₂] = 4.1x10^-4, [NO] = 0.300, [O₂] = 0.375

• [NO₂] = 2.05x10^-4, [NO] = 0.600, [O₂] = 0.750

• [NO₂] = 2.05x10^-4, [NO] = 0.300, [O₂] = 0.375

Cl₂ gas undergoes homolytic cleavage into chlorine atoms at 1100^oC. Kp at 1100^oC for this process is 1.13 x 10^-4. If a sample with an initial Cl₂ gas pressure of 0.500 atm was allowed to reach equilibrium, what is the total pressure in the flask?

Cl₂(g) ↔ 2 Cl(g)

use 5% rule

• 0.496 atm

• 0.00376 atm

• 0.500 atm

• 0.504 atm

Consider the following reaction:

NiO(s) + CO(g) ↔ Ni(s) + CO₂(g)

Kc = 4.0 x 10³ (at 1500 K).

If a mixture of solid nickel (II) oxide and 0.10 M carbon monoxide is allowed to come to equilibrium at 1500 K, what will be the equilibrium concentration of carbon dioxide?

• 0.0 M

• 0.10 M

• 0.05 M

A mixture of 0.10 mol of NO, 0.050 mol of H₂, and 0.10 mol of H₂O is placed into a 1.0-L vessel at 300 K.

At equilibrium, [NO] = 0.062 M.

Determine the equilibrium concentrations of H₂, N₂, and H₂O, then determine Kc.

2 NO(g) + 2 H₂ (g) ↔ N₂(g) + 2 H₂O(g)

• Kc = 670

• Kc = 3.58

• Kc = 0.501