How many grams of MgCl2 (molar mass = 95.20 g/mol) will be formed from 25.6 mL of a 0.100 M HCL solution reacting with excess magnesium metal? (The other product is hydrogen gas.)

The balanced equation for the above reaction is as follows;

Mg + 2HCl - - - > MgCl₂ + H₂

stoichiometry of HCl to MgCl₂ is 2:1

we have been told that Mg is in excess therefore HCl is the limiting reactant

number of HCl moles reacted - 0.100 mol/L x 0.0256 L = 0.00256 mol

according to molar ratio, number of MgCl₂ moles formed - 0.00256/2

Therefore number of MgCl₂ moles formed - 0.00128 mol

mass of MgCl formed - 0.00128 mol x 95.20 g/mol = 0.122 g