can someone plz help i dont understand how to do this?

Question

Phosgene was used as a poisonous gas in World War I. At high temperatures it decomposes as follows:


COCl2(g) ↔ CO(g) + Cl2(g)


with Kc = 4.6×10-3 at 800 K. A sample of 6.76 g of COCl2 is placed in a 1.00-L reaction vessel and heated to 800 K. What are the equilibrium concentrations of all of the species? Enter concentration for COCl2 first, then for CO and then for Cl2.

also what fraction of COCl2 has decomposed?

Answer 1

We can use moles, since the volume is 1 litre.

Moles of phosgene originally = 6.76/99

Moles of phosgene at equilibrium = 6.76/99 - x

Moles of CO = moles of Cl2 at equilibrium = x

x squared/(6.76/99 - x) = 4.6 x 10-3.

Now solve for x.