Question

Consider the following equilibrium system at 900°C:

H20(g) + CO(g) <==> H2(g) + CO2(g)

Initially 5.0 moles of H2O and 4.0 moles of CO were reacted. At equilibrium, it is found that 2.0 moles of H2 are present. How many moles of H2O remain in the mixture?

Would be greatly thankful if someone could help me!

Answer 1

I have removed the (g) designation in order to get all of this on one line.

..........H20 + CO <==> H2 + CO2
I.........5.0...4.0.....0.....0
C.........-x.....-x.....x.....x.
E.......................2.........

If 2.0 mols H2 are present at equilbrium then x must be 2.0 mols H2. That means mols H2O used must have been x = 2.0 so 5.0-2.0=3.0
You also know that mols CO2 at 4quilibrium = 2.0 and mols CO remaining = 4-2=2

Answer 2

Thanks very much!