posted by ALEX .
Magnesium metal reacts with HCl solution, liberating H2 gas and generating Mg2+ cations in solution. A 2.335-g sample of Mg metal is added to 50.0 mL of a 4.00 M HCl solution, and the reaction goes to completion. How many grams of H2 are formed?
Mg+2HCl>>H2 + MgCl2
moles of Mg= 2.335/atomicmassMg
so you get the same number of moles of H2.