[Super Newb]

For a chemical reaction of H2 (g) + I2 (g) 2HI (g), ΔH = - 200 kJ mol^-1 , 0.100 mol of H₂ (g) at a pressure of 0.522 atm and 0.100 mol of I₂ at a pressure of 0.656 atm were mixed at 10^oC. The final pressure after equilibrium had been established was 0.70 atm.

Calculate
(a) the equilibrium constant, K_p.

(b) the equilibrium constant, K_c
.(Given R = 0.0821 L atm mol^-1 K^-1)


(c) the equilibrium concentrations of H₂, I₂ and HI in mol dm^-3

[Borek]

You have to show your attempts at solving the question to receive help. This is a forum policy.

[Super Newb]

I need help desperately, I will be having exam in few hours time.

K_p
=(P_HI)²/(P_H2×P_I2)
=(2x)²/(0.35-x)²

I have no idea how to find x

Other relevant equations (I think)
K_p=K_c(RT)^Δn = K_c (since Δn=0)
ΔG^Θ=-RTln(K_eq)
ΔG^Θ=ΔH^Θ-TΔS^Θ

[Borek]

Strange question. Pressure should not change, as the number of moles of gas produced is identical to the number of moles of gas consumed. So the only way the pressure can change is due to the fact temperature changes - perhaps that's why you are given ΔH, but you would need Cp as well. Or perhaps you are expected to estimate ΔS and calculate ΔG...

Sorry, I don't see any obvious approach. Perhaps I need more coffee.

[Super Newb]

Do help me after you had sufficient caffeine to competitively antagonist your adenosine receptor.