Question

For the following reaction
Co(g)+H2o(g)=Co2(g)+H2(g)
If the initial concentrations of Co and H2o are 1.00 mol in a 50 L vessel, what is the number of mole of each species at equilibrium, if the equilibrium constant Kc= 0.85 at 1000 C?

please can any one explain how to do this ?

Answer 1

the two reactants react in equal amounts to give two products in equal amounts

let x = concentration of each product

Kc = 0.85 = [x]^2 / [1.00 - x]^2

.85 - 1.7 x + .85 x^2 = x^2

.15 x^2 + 1.7 x - .85 = 0

use quadratic formula to find x

moles = concentration * vessel size

Answer 2

should I use 1mole/50L =0.02 M instead of using 1 ?

Answer 3

Yes, you should use 1/50, calculate as shown above but x will be concentration and not mols. Then convert x = concentration in mols/L to mols.