If 35.0 mL of 0.210 M HCl reacts with excess Mg, how many mL of hydrogen gas are produced at STP?

Question

Mg(s) + 2HCl(aq) → MgCl2(aq) + H2(g)

Answer 1

mols HCl = M x L = ?
Using the coefficients in the balanced equation, convert mols HCl to mols H2 gas.
Now convert mols H2 gas to L. L H2 = mols H2 x 22.4 L/mol = ? L.