Calculating the number of moles of H2 gas

First determine and balance the chemical equation of the reaction. Identify the compounds involved.

Mg_(s) + 2HCl_(aq) ® H_2(g) + MgCl_2(aq)

Follow the flow chart for determining the number of moles of Hydrogen gas.

		Divide by molar mass			Multiply by mole ratio
Mass of Mg			Moles of Mg			Moles of H2 gas