Question

At 35 degrees Celcius,
K = 1.6x10^-5
for the reaction:
2NOCl<--> 2NO + Cl2

If 2.0mol NOCl and 1.0mol Cl2 are placed into a 1.0-L flask, calculate the equilibrium concentrations of all species.

Answer:
[NOCl] = 2.0M
[NO] = 8.0x10^-3
[Cl2] = 1.0M

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What I did:
___2NOCl<--> 2NO + Cl2
I__2.0_______0_____1.0
C__-2x_______+2x___+x
E__2-2x______2x_____1+x

K = 1+x * 2x^2 / (2-2x)^2
x = -0.99987 or x = 5.609x10^-3 or x = -5.705x10^-3

I am obviously doing something wrong.
Please help - I at least tried my homework.

Answer 1

K = 1+x * 2x^2 / (2-2x)^2
<b>One quick thing I see is the 2x^2 came from (2x)^2 so that would be 4x^2.</b>

Answer 2

Here is a cubic equation solver if you need one. My answer was x = 0.003976 which rounds to 0.004 so (NO) = 0.008M
http://www.1728.com/cubic.htm