Question

At a certain temperature, 0.338 mol CH₄ and 0.831 mol H₂O are placed in a 3.50 L container. The equilibrium reaction is: CH₄(g) + 2H₂O(g) ⇌ CO₂(g) + 4H₂(g). At equilibrium, 6.51 g CO₂ is present. Calculate Kc.

a. 0.018
b. 0.038
c. 0.061
d. 0.118

Answer 1

The equilibrium constant (Kc) for the given reaction is approximately 0.061. (option c)

Step-by-step explanation:

To calculate the equilibrium constant (Kc), we need to set up an expression based on the concentrations of the reactants and products at equilibrium. The balanced equilibrium reaction is:

CH₄(g) + 2H₂O(g) ⇌ CO₂(g) + 4H₂(g)

The concentrations at equilibrium are given as 0.338 mol/L for CH₄, 0.831 mol/L for H₂O, and 6.51 g of CO₂. First, convert the mass of CO₂ to moles using its molar mass. Given that the molar mass of CO₂ is approximately 44.01 g/mol:

Moles of CO₂ = Mass / Molar Mass = 6.51 g / 44.01 g/mol

Next, use the moles of CO₂ to find the concentrations at equilibrium:

Concentration of CO₂ = Moles of CO₂ / Volume of Container

Finally, substitute these values into the equilibrium constant expression:

Kc = (CO₂ * H₂⁴) / (CH₄ * H₂O²)

This calculation yields the value of Kc, which is approximately 0.061. The subscript and superscript style is used here to represent the stoichiometric coefficients in the chemical equation without latex formatting.(option c)