For this stoichiometry problem, we need to first, set up the properly balanced equation, which the question already provided us:
2 CO + O2 -> 2 CO2
We have:
5.0 moles of CO
6.0 moles of O2
Notice that we have two values for the reactants, this means that we need to find which one is the limiting and which one will be the excess reactant, let's try CO first:
From the molar ratio of the reaction, which is 2:1, 2 moles of CO for 1 mol of O2, we need to see if it makes sense 5 moles of CO for 6 moles of O2
2 CO = 1 O2
5 CO = x O2
x = 2.5 moles, therefore we have O2 in excess, since we only need 2.5 moles of O2 to react with 5 moles of CO
Using the limiting reactant, 5 moles of CO, now we can identify the number of moles of CO2, by the molar ratio between CO and CO2, which is 2:2, 2 moles of CO will produce 5 moles of CO2, therefore if we have 5 moles of CO, we will also have 5 moles of CO2
It will be produced 5 moles of CO2