## 2013 Final Q5C

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Joined: Thu Jul 27, 2017 3:01 am

### 2013 Final Q5C

Consider the follow reaction: Ni(CO)4(g) <--> Ni(s) + 4 CO(g)
If the initial concentration of Ni(CO)4(g) is 1.0 M, and "x" is the equilirium concentration of CO(g), write a general expression for the equilibrium constant Kc in terms of x.

For this problem, I used an ICE Table to get my values. Once I got my values, I basically input it to the Kc, where I said it was (4x^4)/(1-x), which is the wrong answer.

(The right answer is (x^4)/(1-x/4) )

What did I do wrong? Or am I mathematically incompetent?

Vivian Nguyen
Posts: 66
Joined: Fri Sep 29, 2017 7:04 am
Been upvoted: 2 times

### Re: 2013 Final Q5C

You're not mathematically incompetent! Stay positive before finals :)

Here's what the ice chart should look like

_____Ni (CO)4_____4CO
I____1.0___________0
C___X/4__________4(X/4)
E ___1 - X/4_______X

Kc = X^4 / (1 - X/4)

Because the equilibrium concentration of CO is X, it means that the change in molarity in the ice chart is only a quarter of that because the coefficient is 4. As a result, the change is really x/4, not x.

Hope this helps!