[biozeta]

At a particular temperature, Kc= 1.6 x 10^-2 for:
2H2S (g) <--> 2H2 (g) + S2 (g)
Calculate Kc for each of the following reactions:
a. 1/2 S2 (g) + H2 (g) <--> H2S (g)
b. 5 H2S (g) <--> 5 H2 g) + 5/2 S2 (g)

I'm not sure where to start at all. I know Kc is the rate of reaction at equilibrium, but what does 1.6 x 10^-2 have to do for the other reactions? Don't I have to have an initial concentration for each element?
Thanks!

[sjb]

At a particular temperature, Kc= 1.6 x 10^-2 for:
2H2S (g) <--> 2H2 (g) + S2 (g)
Calculate Kc for each of the following reactions:
a. 1/2 S2 (g) + H2 (g) <--> H2S (g)
b. 5 H2S (g) <--> 5 H2 g) + 5/2 S2 (g)

I'm not sure where to start at all. I know Kc is the rate of reaction at equilibrium, but what does 1.6 x 10^-2 have to do for the other reactions? Don't I have to have an initial concentration for each element?
Thanks!

Kc is nothing to do as such with the rate of reaction, more a measure of the equilibrium concentrations of everything.

What are your expressions for Kc for all three reactions?