Question

Consider the following reaction.

A (aq) --> 2B (aq)

Kc = 2.40 x 10^-6

If a 1.70 M sample of A is heated to 500 K, what is the concentration of B at equilibrium?

Answer 1

A (aq)    <—>    2 B (aq)

1.70           0       (initial)

1.70-x       2x       (at equilibrium)

Kc = [B]^2/[A]

Kc = (2x)^2/(1.70-x)

Assuming x can be ignored as compared to 1.70

So, above expression becomes

Kc = (2x)^2/(1.70)

so, 2x = sqrt (Kc*c)

2x = sqrt ((2.4*10^-6)*1.7) = 2.02*10^-3

At equilibrium,

[B] = 2x = 2.02*10^-3 M

Answer: 2.02*10^-3 M