help: Calculate the value of the equilibrium constant, Kc

Question

A mixture initially contains A, B, and C in the following concentrations:  A= 0.350M  ,  B= 1.35M  , and  C= 0.300 M . The following reaction occurs and equilibrium is established:

A+2B ⇌ C

At equilibrium,  A= 0.160M  and  C= 0.490 M . Calculate the value of the equilibrium constant, Kc

Answer 1

Use an ICE table.

A + 2B ==> C

0.35...1.35....0.3 ... Initial

-x.....-2x.......+x.......Change

0.35-x..1.35-2x...0.3+x...Equilibrium

0.35 - x = 0.160

x = 0.19 = [A]

1.35 - 2x = 1.35 - 0.38; x = 0.97 = [B]

0.3 + 0.19 = 0.49 = [C]

Kc = [C] / [A][B]²

Kc = (0.49) / (0.19)(0.97)²

Kc = 2.74