Question

How many CO2 molecules would be formed from the reaction mixture that produces the greatest amount of products?

2CH3OH(g)+3O2(g)--->2CO2(g)+4H2O(g)

3-CH3OH & 3-O2
or
1-CH3OH & 6-O2
or
4-CH3OH & 2-O2

Answer 1

It takes 2 molecules CH3OH and 3 molecules O2 to form 2 molecules CO2. These are the stoichiometric amounts needed. Anything less than that, #2 has CH3OH as the limiting reagent and #3 has O2 as the limiting reagent. Therefore, #1 is the best fit if your purpose is to produce as much CO2 as possible.

1 molecule CH3OH and bunches of oxygen will produce ONLY 1 molecule CO2.

4 molecules of CH3OH and 2 O2 will produce only 1-1/3 molecules.