Calculate the mass and volume of hydrogen released by the interaction of 4 grams of calcium with hydrochloric acid.

1. Let’s compose the equation of the chemical reaction:
Ca + 2HCl = CaCl2 + H2.
2. Find the chemical amount of calcium:
n (Ca) = m (Ca) / M (Ca) = 4 g / 40 g / mol = 0.1 mol.
3. Using the reaction equation, we find the chemical amount, and then the mass and volume of hydrogen (Vm is the molar volume, constant equal to 22.4 l / mol):
n (H2) = n (Ca) = 0.1 mol.
m (H2) = n (H2) * M (H2) = 0.1 mol * 2 g / mol = 0.2 g.
V (H2) = n (H2) * Vm = 0.1 mol * 22.4 L / mol = 2.24 L.
Answer: m (H2) = 0.2 g; V (H2) = 2.24 l.