Chem questions

[the prodogy]

1-For the reaction N2(g) + O2(g) <===> 2NO(g), the equilibrium constant is K1. The equilibrium constant is K2 for the reaction 2NO(g) + O2(g) <===> 2NO2(g), What is K for this reaction?

NO2(g) <===> (1/2) N2(g) + O2(g)

a.[1/K1K2]1/2
b.1/ (4K1K2)
c.1/ (2K1K2)
d.1/ (K1K2)



2-Consider the reaction:

N2O4(g) <===> 2 NO2(g).​

If 0.020 mol of N2O4(g) is placed in a 500-ml container and allowed to reach equilibrium, [N2O4] = 0.0055 M. What is Kc for the reaction?



a.0.870
b.12.5
c.6.27
d.0.138

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[mshopeful]

1. Notice that if you flip those first two reactions, add them together, then divide by two, you get your final reaction.
I'm not sure on this part, but I think since we flipped the reaction, the K will change to either -K or 1/K. Looking at possible answer choices, it's probably 1/K

I know that when you take the sum of two reactions, the Kc for the final reaction is the product of the other Kc's.

So I'm guessing the answer is (1/K1K2)(1/2). Divide by 2 because we divided the reaction by 2 earlier.

??? Taking a shot since no one answered...

 

[TheRighteous]

K1 = [NO]^2/([O2][N2])
K2 = [NO2]^2/([02][NO]^2)

K for your reaction = [O2][N2]^0.5/[NO2]
Relationship of the three equations:
K = [(1/K1)(1/K2)]^0.5

Answer is A.