Question

In the reaction below the equilibrium constant was found to be 2.80 x102. What is the concentration of SO3 at equilibrium if the equilibrium concentrations of SO2 and O2 are 0.124 M and 0.031M respectively? O2(g)+SO2(g)=SO3(g)

Answer 1

For a chemical reaction aA + bB --> cC + dD, the equilibrium constant is Keq = ({C}^c*{D}^d)/({A}^a*{B}^b) where {A}, {B}, {C} and {D} denote the concentration of A, B, C and D resp.

The equilibrium expression for the reaction is
Keq = [SO3]^2 /[SO2]^2 * [O2]

Let x equal the concentration of SO3 at equilibrium.
Substituting into the value of Keq given and the equilibrium concentrations you have

2.80 x10^2 = (x)^2/(0.124)^2 * (0.031)

==> x^2 = 0.1335
==> x = 0.365

Therefore, [SO3]eq is 0.365 M