Question

2SO2 + O2 ---------- 2SO3
When a 2:1 ration of SO2 and O2 at a total initial pressure of 3atm is passed over a catalyst, the equilibrium partial pressure of SO3 is found to be 1.9 atm.
calculate the equilibrium partial pressure of SO2 and O2 and hence the new total pressure.

Answer 1

I think this is a tough question but you can do it step by step: The initial pressure is 3atm so that's 2 atmospheres from sulphur dioxide and one from oxygen. It looks like 95% of the initial reactants are converted to sulphur trioxide, since the partial pressure at equilibrium is 1.9 atm. If 100% had been converted then the pressure would have been 2 atm since there was a third less gas molecules than before the reaction. So that's 5% of the initial pressure from the reactants or 0.15 atm plus 1.9 or 2.05atm. I hope this is correct and makes sense to you, best wishes,