If the initial pressure of HD(g) is 8.913 atm, calculate the % decomposition of HD(g) when the reaction comes to equilibrium according to the balanced equation. The value of Kp at 1000 K is 0.26. The initial pressure of the reaction products is 0 atm.

Question

2HD(g) = H2(g)+D2(g)

So I set it up using the ice method. with the i step already given. So for the c step, I put -2x going in the forward direction arrow and +x under H2 and D2. Then I set up the e step with (8.913-2x) under 2HD and x under the products. I then set up the Kp equation with equilibrium products over reactants. But I don't know if that last step is correct or not. If it isn't, how am I supposed to proceed?

Answer 1

You're right on target. Solve the equation you've set up. Then
% decomp = (2x/8.913)*100 = ?

Answer 2

Yes, but what do I put in for x? That's were I got stuck.

Answer 3

oh wait. I set up the equation
0.26=(x^2)/(8.913-2x).
my x=2.032476713
then I used the % decomp equation and got...0.45607017 so 45.6%

Answer 4

Yes, x comes from the solution of your ICE table. I didn't check you math but that's what you do.