Determine the mass of a solution with a mass fraction of sodium hydroxide of 5% required

Determine the mass of a solution with a mass fraction of sodium hydroxide of 5% required for interaction with nitric acid weighing 12.6 g.

1.Let’s find the amount of nitric acid substance by the formula:

n = m: M.

M (HNO3) = 63 g / mol.

n = 12.6 g: 63 g / mol = 0.2 mol.

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

NaOH + HNO3 = NaNO3 + H2O.

For 1 mol of potassium hydroxide there is 1 mol of acid. Substances are in quantitative ratios 1: 1.

The amount of sodium hydroxide substance and nitric acid will be equal. n (NaOH) = n (HNO3) = 0.2 mol.

Find the mass of sodium hydroxide.

m = n × M,

M (NaOH) = 40 g / mol.

m = 0.2 mol × 40 g / mol = 8 g.

3. Find the mass of the solution containing 5% NaOH.

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

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

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

m (solution) = (8 g: 5%) × 100% = 160 g.

Answer: 160 BC