How many grams of alkali can be obtained by reacting 112 grams of calcium oxide with water.

Given:                     112 g                 x g

m (CaO) = 112 g CaO + H2O = Ca (OH) 2

m (Ca (OH) 2) -?    56 g / mol    74 g / mol

M (CaO) = 40 + 16 = 56 g / mol;

M (Ca (OH) 2) = 40 + 16 ∙ 2 + 1 ∙ 2 = 74 g / mol;

ν = m / M; ν (CaO) = 112 g / 56 g / mol = 2 mol;

ν (CaO): ν (Ca (OH) 2) = 1: 1;

ν (Ca (OH) 2) = 2 mol;

m = ν ∙ M;

m (Ca (OH) 2) = 2 mol ∙ 74 g / mol = 148 g.

Answer: You can get 148 g (Ca (OH) 2) by reacting 112 g CaO with H2O.