For the reaction below, Kc = 9.2 × 10⁻⁵. What is the equilibrium concentration of D if the reaction begins with 0.30 M A?

Question

A (aq) + 2 B (s) ⇌ C (s) + 2 D (aq)

Answer 1

Have you used an ICE box before?

A (aq) + 2 B (s) ⇌ C (s) + 2 D (aq)

I 0.30 n/a n/a 0

C -x n/a n/a +2x

E 0.3-x n/a n/a 2x

K=[D]²/[A]

9.2*10^-5=[2x]²/[0.3-x]

0.3-x is essentially the same as 0.3, so

9.2*10^-5=[2x]²/[0.3]

solve for x

9.2*10^-5=4x²/[0.3]

x=0.00263

Equilibrium concentration of D is the 'E' row of the ice box, so

[D]_equilibrium=2x

2(0.00263)=0.00526