Question

A system is represented by the following equation:
2A(aq) + B(aq) --> 3C(aq)

At equilibrium, [C]=0.6 M. Calculate the value of K if initially 1 mol of A and 2 mol of B were placed in a 1 L flask.

Answer 1

we will assume that the aqueous solutions fill the 1 L flask.

At start

1 mol A + 2 mol B and 0 mol C

At equilibrium

1-2x mol of A and 2-x mol of B and 3x mol of C

so x=0.2 M

K=x^3/(1-2x)^2(2-x)

K=(0.2)^3/(0.6)^2(1.8)

K=0.008/(0.36)(1.8)

K=0.012 (with no units)

Answer 2

I am having trouble with this question so I decided to check online. The question sheet in which I got this question from came with an answer sheet, and it says the answer for k = 0.33. Another online source gave an answer of 0.024. I'm not sure what values are needed in the change row.

2A + B <----> 3C
INITIAL 1 2 0
CHANGE +3X
EQUILIBRIUM 0.6 M

If 0.6 = 3x, x should equal 0.2? How is x affecting A + B?