Calculate the amount of substances and the mass of calcium hydroxide if 80 g of calcium

Calculate the amount of substances and the mass of calcium hydroxide if 80 g of calcium is taken for the reaction with water.

Given:
m (Ca) = 80 g

To find:
n (in-in) -?
m (Ca (OH) 2) -?

Decision:
1) Ca + 2H2O => Ca (OH) 2 + H2 ↑;
2) M (Ca) = Mr (Ca) = Ar (Ca) = 40 g / mol;
M (Ca) = Mr (Ca) = Ar (Ca) + Ar (O) * 2 + Ar (H) * 2 = 40 + 16 * 2 + 1 * 2 = 74 g / mol;
3) n (Ca) = m (Ca) / M (Ca) = 80/40 = 2 mol;
4) n (H2O) = n (Ca) * 2 = 4 mol;
n (Ca (OH) 2) = n (Ca) = 2 mol;
n (H2) = n (Ca) = 2 mol;
5) m (Ca (OH) 2) = n (Ca (OH) 2) * M (Ca (OH) 2) = 2 * 74 = 148 g.

Answer: The amount of Ca substance is 2 mol; H2O – 4 mol; Ca (OH) 2 – 2 mol; H2 – 2 mol; weight of Ca (OH) 2 – 148 g.