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I have a few questions about my homework: (it is a rather long post, but I explained my work in detail, so everything is very clear -I hope-).

1) When we have a reaction such as: SO2 (g) + 1/2O2 (g) <=> SO3 (g) and then we have:

2SO2 (g) + O2 (g) <=> 2SO3 (g), we calculate Kc of the second reaction as = the first Kc squared. Correct? Why isn't it 2Kc? Is there a case where we would have Kc being twice as much?

2) We have the following reaction:

N2 (g) + 3H2 (g) <=> 2NH3 (g). Kp = 4.51 x 10^(-5) at 450 degrees celsius.

We are given values for each of the reactants and product.

105 atm NH3, 35 atm N2 and 495 atm H2.

We have to calculate whether the reaction is at equilibrium or not at 450.

Which I did by calculating Kp by plugging in the values, and then comparing my result to the value of Kp given at the begining of the problem. I got 1.20 x 10^(-3), which is not the same, and therefore the reaction is not at equilibrium. Correct?

But then, I have to indicate in which direction the mixture must shift in order to achieve equilibrium. I can't seem to figure out how I should do that.

Do I calculate Qp and then see which is bigger? (Qc bigger, it shift to the left, Qc smaller, it shifts to the right).

The thing is, I must be forgetting something, because I don't know which values to use to get Qp.

3) We have a mixture of 1.374g of H2 and 70.31 g of Br2, heated in a 2.00L vessel at 700K. We get this reaction:

H2 (g) + Br2 (g) <=> 2 HBr (g)

At equilibrium, we have H2 = 0.566g. We need to calculate the equilibrium concentrations of H2, Br2, HBr, and calculate Kc.

For some reason, I am blocking on this problem. Could you give me some pointers so I can start thinking in the right direction?

Thank you,

J.