# Keq for excess

1. Mar 17, 2015

### supercalaf123

If i'm trying to find the Kc for A + B --> C and we know that A is in excess, pushing the reaction to the right. At equilibrium, B is 0 essentially. My question is for calculating Kc = [C]/[A][ B ] do we use the equation Kc = [C]/[A] because [ B ]is essentially 0 at equilibrium?

2. Mar 17, 2015

### Staff: Mentor

So you are saying

$$0 \times large~number = large~number$$

Does it look like something that can be true?