For the reaction below, Kc = 1.10 × 10⁻⁴. What is the equilibrium concentration of C if the reaction begins with 0.200 M A and 0.150 M B? 2 A (aq) + B (aq) ⇌ C (aq)

Answer 1

2A(aq) + B(aq) <==> C(aq)

Equilibrium expression is

K = [C] / [A]²[B]

Prepare an ICE table:

2A(aq) + B(aq) <==> C(aq)

0.2..........0.15...............0........Initial

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

0.2-2x....0.15-x............x........Equilibrium

Substitute in the equilibrium expression:

1.10x10^-4 = (x) / (0.2-2x)²(0.15-x) ... b/c K is small, we can essentially avoid using the quadratic as follows..

1.1x10^-4 = x/(0.2)2(0.15)

x = (2.2x10^-5) (1.65x10^-5)

x = 3.63x10^-10 M = [C]