Question

Consider the following chemical equilibrium:

C(s)+ 2H2(g) ⇌ CH4(g)

Now write an equation below that shows how to calculate Kp from Kc for this reaction at an absolute temperature . You can assume is comfortably above room temperature.

Answer 1

Kc = [CH₄] / [H₂]²

Kp = [CH₄] / [H₂]² * (0.082*T)^-1

Step-by-step explanation:

Equilibrium constant, Kc, is defined as the ratio of the concentrations of the products over the reactants. Also, each concentration of product of reactant is powered to its coefficient.

Pure solids and liquids are not taken into account in an equilibrium

Thus, for the reaction:

C(s)+ 2H₂(g) ⇌ CH₄(g)

Equilibrium constant is:

Kc = [CH₄] / [H₂]²

Now, using the formula:

Kp = Kc* (RT)^Δn

Where R is gas constant (0.082atmL/molK), T is the temperature of the reaction and Δn is difference in coefficients of gas products - coefficients of gas reactants (1 - 2= -1)

Replacing:

Kp = [CH₄] / [H₂]² * (0.082*T)^-1