# Chemistry Equilibrium Kc

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1. Feb 13, 2019

1. The problem statement, all variables and given/known data
Kc = 1.37 for HI(g) ↔ 1/2 H2(g) + 1/2 I2(g). What is Kc (to 3 decimal places) for H2(g) + I2(g) ↔ 2HI(g)?

2. Relevant equations
Kc= Products/Reactants, Ice Tables

3. The attempt at a solution
I tried an ice table, but I’m not sure what to do with the Kc value I’m given when I have to another Kc value

2. Feb 13, 2019

### Wrichik Basu

$$K_{c_1} = 1.37 = \dfrac{[H_2]^{1/2} [I_2]^{1/2}}{[HI]}$$ and $$K_{c_2} = \dfrac{[HI]^2}{[H_2][I_2]}$$ Can you find a relation between $K_{c_1}$ and $K_{c_2}$?

3. Feb 13, 2019

I know the reaction reversed and doubled. But I don’t know how to solve for Kc mathematically with this set-up.

4. Feb 13, 2019

### Wrichik Basu

What maths are you referring to? If you can find $K_{c_2}$ in terms of $K_{c_1}$, then can't you find $K_{c_2}$?

5. Feb 13, 2019

### Staff: Mentor

What do you get if you square @Wrichik Basu's first equation, and then multiply it by his second equation.