MarcMTL

1. The problem statement, all variables and given/known data

Sulfur dioxide reacts with the oxygen in humid air to produce sulfur trioxide.

After the reaction, how many moles are left of: SO₂, O₂ and how many moles of SO₃ were created?


2. Relevant equations

2 SO₂ + O₂ --> 2 SO₃

3. The attempt at a solution
The limiting reactant is SO₂, so we know that it will fully react and we'll end up with 0 moles of SO₂.

From previous steps, I know that I have 0.1021 moles of SO₂, and 0.0857 moles of O₂. I also know that after the reaction, I will have 0.03474 moles of O₂ left.

I can't, for the life of me, figure out how many moles of SO₃ I'll have at the end.
Shouldn't there be some conservation of mass? I keep finding that I'll have 0.1021 moles of SO₃ at the end, which is the same amount as the SO₂.

Is this correct? I seem to think that the reaction with O₂ will have changed the number of moles.