If you have 6 moles of reactant a and excess of b and c, how much product e would be formed?

To be able to solve this problem, we must be given the balanced chemical equation:

3A + 5B + 1C ---> 2D + 1E

Our reactant A is called the limiting reactant because it is limited in amount which is only 6 moles. So we based our calculation on that reactant alone.

From stoichiometry, we have 1 mole of E for every 3 moles of A, therefore:

moles E = 6 moles A * (1 mole E / 3 moles A)

moles E = 2 moles