[docnet]

Hello, this is one of the equilibrium problems that I've been trying to solve, but there isn't an answer from the book that I can compare my answer to. Please let me know if this is the correct way to approach this type of problem.



Given:

Consider the following reaction at a certain temperature

A₂+B₂ 2AB

The mixing of 1 mole of A₂ with 3 moles of B₂ gives rise to x mole of AB at equilibrium. The addition of two more moles of A₂ produces another x mole of AB. What is the equilibrium constant for the reaction?

I set up two reaction quotients to represent the concentrations of each situation at equilibrium, and set the quotients equal to each other assuming that the K_c for the reactions is constant.


First I used x to represent the moles of reacted A₂ and B₂ for the left reaction, and 2x for the right reaction, but then I realized that the two x's don't represent the same molar concentration. So I used y to represent the concentration for the second reaction.

(2x)²/[(1-x)(3-x)] = (2y)²/[(3-y)(3-y)]

Then I let 2x=y based on the given information that two x moles of AB is produced after the addition of A₂.

Then I substituted 2x into y.

(2x)²/[(1-x)(3-x)] = (4x)²/[(3-2x)(3-2x)]

x = 3/4

Plugging in 3/4 into the the equilibrium expression gave 4 as the equilibrium constant. Would this be an acceptable answer?

Thanks in advance for any input.

[docnet]

After some thinking I realized that there is no need for y. I probably incorrectly plugged in 2x on my first try and confused myself unnecessarily.