The reaction between Magnesium and Hydrogen Chloride is:
Mg + 2 HCl → MgCl₂ + H₂
The balloon will inflate because gas is liberated in the presence of H₂.
Let's compute which of the reactants is limiting. The solution is as follows:
Molar mass of Mg = 24.305 g/mol Molar mass of HCl = 36.45 g/mol
Flask A: Moles HCl needed = 7.23 g Mg*(1 mol/24.305 g)*(2 mol HCl/1 mol Mg) = 0.595 moles Since the available mass of Mg needs 0.595 moles of HCl, and HCl has excess amounts of 1.05 moles, the excess reactant is HCl and the limiting reactant is Mg. So, let's base our production on Mg. The more H₂ produced, the bigger the balloon.
Flask A: Moles H₂ produced = 7.23 g Mg*(1 mol/24.305 g)*(1 mol H₂/1 mol Mg) = 0.297 moles
Flask B: Moles H₂ produced = 1.22 g Mg*(1 mol/24.305 g)*(1 mol H₂/1 mol Mg) = 0.05 moles
