I don't know where to begin....?

Question

Consider the following equilibrium: 2A <===> B. Let K = 2.924 and let the initial concentrations be A0 = 0.967 and B0 = 0.149. What is the equilibrium concentration of A in units of mol/L?

Even if someone knows what equation that would help. Thanks in advance.

Answer 1

2A &lt;===&gt; B

Kc = [B] / [A]^2 = 2.924

First, you need to see which way the system will go to establish equilibrium  That means you need to compute Q.

Q looks just like Kc, only different.   It&#039;s not at equilibrium.

Q = [B] / [A]^2 = 0.149 / 0.967^2 = 0.159

Since Q is less than Kc, we know that the system will move to the right in order to establish equilibrium.  

At equilibrium [A] = 0.967 - 2x, [B] = 0.149 + x

Kc = [B] / [A]^2 = (0.149 + x) / (0.967 - 2x)^2 = 2.924

x = 0.290

[A] = 0.967 - 2(0.290) = 0.387M