Determine the mass of a nitric acid solution with a mass fraction of 5% required to obtain calcium

Determine the mass of a nitric acid solution with a mass fraction of 5% required to obtain calcium nitrate from calcium oxide weighing 11.2 g.

1.Let’s find the amount of calcium oxide substance by the formula:

n = m: M.

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

n = 11.2 g: 56 g / mol = 0.2 mol.

2. Let’s compose the reaction equation. Let’s find in what quantitative ratios the substances are.

CaO + 2HNO3 = Ca (NO3) 2 + H2O.

For 1 mole of calcium oxide, there are 2 moles of nitric acid.

The substances are in quantitative ratios of 1: 2.

The amount of nitric acid substance is 2 times more than the amount of calcium oxide substance.

2n (HNO3) = n (CaO) = 0.2 × 2 = 0.4 mol.

3. Find the mass of nitric acid.

m = n × M,

M (HNO3) = 63 g / mol.

m = 0.4 mol × 63 g / mol = 25.2 g.

The mass fraction of a substance is calculated by the formula:

W = m (substance): m (solution) × 100%,

hence m (solution) = m (substance): w) × 100%.

m (solution) = (25.2 g: 5%) x 100% = 504 g.

Answer: m (solution) = 504 g.