Answer:
68
Explanation:
First, we will calculate the molar concentration (M) of each substance using the following expression.
M = mass of the substance / molar mass of the substance × volume of solution
CO₂
M = 2.25 g / 44.01 g/mol × 8.6 L = 0.0059 M
H₂O
M = 2.72 g / 18.02 g/mol × 8.6 L = 0.018 M
CH₃OH
M = 3.82 g / 32.04 g/mol × 8.6 L = 0.014 M
O₂
M = 1.98 g / 32.00 g/mol × 8.6 L = 0.0072 M
Let's consider the following reaction at equilibrium.
CO₂(g) + H₂O(g) ⇄ CH₃OH(l) + O₂(g)
The concentration equilibrium constant (Kc) will not include CH₃OH because it is a pure liquid. Then,
Kc = [O₂] / [CO₂] × [H₂O]
Kc = 0.0072 / 0.0059 × 0.018
Kc = 68