Consider the following equation (I know the equation is not balanced, its just a random example I've created):
5C
2H
4O + 2H
2 
3C
2H
6O
A gaseous mixture consisting of 50 mol% H
2 and 50 mol% C
2H
4O before a reaction was 5 moles. After reaction, it was found that the total number of moles left was 2. Here is the mole balance I've created, is it correct?
Moles of C
2H
4O left + Moles of H
2 left + Moles of C
2H
6O produced = 2 mol (total moles left)
(2.5mol -
5x) + (2.5mol -
2x) + 3x = 2 moles
3 3
Where X = mol of C
2H
6O produce.
I'm not sure if the mole balance is correct, especially the 3x part. Can somebody please clarify? Thanks.