Final answer:
The reaction produced 2.0 g of hydrogen gas, which is calculated by subtracting the mass of the calcium chloride from the total mass of the reactants.
Step-by-step explanation:
The question is about a chemical reaction in which calcium (Ca) reacts with hydrogen chloride (HCl) to produce calcium chloride (CaCl2) and hydrogen gas (H2).
Based on the law of conservation of mass, the mass of the reactants must equal the mass of the products.
Here, we have 40.0 g of Ca and 73.0 g of HCl reacting to form 111.0 g of CaCl2 and some amount of hydrogen gas.
To find the mass of hydrogen gas produced, we subtract the mass of calcium chloride from the total mass of the reactants:
Mass of hydrogen = (Mass of calcium + Mass of HCl) - Mass of calcium chloride
Mass of hydrogen = (40.0 g + 73.0 g) - 111.0 g
Mass of hydrogen = 113.0 g - 111.0 g
Mass of hydrogen = 2.0 g
Therefore, the reaction produced 2.0 g of hydrogen gas.