Anne prepares a solution of copper nitrate with a concentration of 30 g/dm³. What mass of copper nitrate did she add to 100cm³ of water, in grams?

3 g

Explanation:

Concentration of copper nitrate needed = 30 g/dm³

Volume of water = 100 cm³ = 0·1 dm³

(∵ 1 dm³ = 1000 cm³)

Let the mass of copper nitrate that should be added to 100 cm³ water be m g

m : 0·1 = 30

∴ m = 3 g

∴ Mass of copper nitrate that should be added to 100 cm³ of water = 3 g