Chemistry: Mole ratios, effect on Kp

[Toadie]

The question I'm working on reads:

 

At 1000 K, K_p = 1.85 for the reaction

 

SO₂(g) + ½O₂(g) ↔ SO(g)

 

What is the value of K_p for the reaction 2SO₂(g) + O₂(g) ↔ 2SO₃(g) ?

 

 

I assumed that the K_p would not change, because the mole ratio was not changed. But the back of the book tells me otherwise. The answer is supposed to be K_p = 3.42.

 

Can someone please explain how to get that answer?

[Capita]

you are doubling the amount of moles there for kp being a constant 1.85 is squared giving you the 3.42

[hermanntrude]

when you reverse the reaction, you take 1/K

 

when you double the reaction, you take K^2

 

when you half the reaction, you take square root(K)

 

when you combine reactions, you multiply the Ks

[Toadie]

Thanks Hermann, that'll probably come in handy on my final tomorrow.