Question

Calculate the percent by mass of potassium nitrate in a solution made from 45.0 g kno3 and 295 ml of water. The density of water is 0.997 g/ml.

Answer 1

Answer:  the percent by mass of potassium nitrate is 13.3%

Explanation:

1) Data:

• Mass of solute, m₁ = 45.0 g

• Volume of solvent, V₂ = 295 ml

• density of water, d₂ = 0.997 g/ml

2) Formulae:

• Percent by mass, % = (mass of solute / mass of solution) × 100

• Density, d = mass / volume

3) Solution:

• d = mass / volume ⇒ m₂ = d₂ × V₂ = 0.997 g/ml × 295 ml = 294. g

• mass of solution = m₁ + m₂ = 45.0g + 294. g = 339. g

• % = (45.0 g / 339. g) × 100 = 13.3 %

• The answer has to be reported with 3 significant figures.