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?

Answer 1

Mg+2HCl>>H2 + MgCl2

moles of Mg= 2.335/atomicmassMg

so you get the same number of moles of H2.

gramsH2=molesH2*molmassH2