# Calcium oxide and hydrochloric acid react. What is the mass of the salt obtained if a solution of hydrochloric

**Calcium oxide and hydrochloric acid react. What is the mass of the salt obtained if a solution of hydrochloric acid with a mass of 100 g with a mass fraction of 20% was taken?**

1. Let’s find the mass of hydrochloric acid in solution by the formula:

m (HCl) = m (solution) * w (solution) / 100% = 100g * 20% / 100% = 20g

2. We compose the reaction equation:

CaO + 2 HCl = CaCl2 + H2O

According to the equation: 2 mol of HCl enters the reaction. We find the mass by the formula: m = n * M

m (HCl) = 2 mol * (1 + 35.5) = 73 g

According to the equation: 1 mol of CaCl2 was formed. We find the mass by the formula: m = n * M

m (CaCl2) = 1 mol * (40 + 35.5 * 2) = 111 g

3. Calculate the mass of salt:

20 g HCl – x g CaCl2

73 g HCl – 111 g CaCl2

Hence, x = 20 * 111/73 = 30.4 g.