What mass of sodium should be taken to prepare an aqueous solution of sodium hydroxide weighing 80 g

| August 8, 2021 | education

What mass of sodium should be taken to prepare an aqueous solution of sodium hydroxide weighing 80 g with a mass fraction of 10%?

1.Let’s find the mass of sodium hydroxide in the solution:

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

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

m (NaOH) = (10% × 80 g): 100% = 8 g.

2.Let’s find the amount of sodium hydroxide substance.

n = m: M,

M (NaOH) = 23 + 16 + 1 = 40 g / mol.

n = 8 g: 40 g / mol = 0.2 mol.

3. Let’s compose the reaction equation.

2 Na + 2H2O = 2NaOH + H2.

According to the reaction equation, 2 mol of sodium accounts for 2 mol of sodium hydroxide, that is, they are in quantitative ratios of 1: 1. The amounts of substances of these substances will be the same.

4. Find the mass of sodium.

m (Na) = n × M,

n (Na) = 0.2 mol.

M (Na) = 23g / mol.

m (Na) = 0.2 mol × 23 mol = 4.6 g.

Answer: 4.6 g.



One of the components of a person's success in our time is receiving modern high-quality education, mastering the knowledge, skills and abilities necessary for life in society. A person today needs to study almost all his life, mastering everything new and new, acquiring the necessary professional qualities.