Consider the following reaction: Mg(s) + 2 HCl (aq) → H2(g) + MgCl2(aq)
If 3.65 mol of magnesium and 3.65 mol of hydrochloric acid are reacted, how many
moles of hydrogen gas are produced?

1.825 moles of hydrogen gas are produced.

Explanation:

The balanced chemical equation is:

According to stoichiometry :

2 moles of require = 1 mole of

Thus 3.65 moles of will require=  of

Thus is the limiting reagent as it limits the formation of product and is the excess reagent.

As 2 moles of give = 1 mole of

Thus 3.65 moles of give =  of

Thus 1.825 moles of hydrogen gas are produced.