Question

A potassium bromide solution is 8.30 % potassium bromide by mass and its density is 1.03 g/mL.

What mass of potassium bromide is contained in 41.2 mL of the solution?
3.52 g
3.32 g
5.11 g
3.42 g

Answer 1

3.52 g.

Step-by-step explanation:

• The density of potassium bromide solution is 1.03 g/mL, which means that the mass of 1.0 mL of the solution is 1.03 g.

Using cross multiplication:

1.0 mL of potassium bromide solution weigh → 1.03 g.

41.2 mL of potassium bromide solution weigh → ??? g.

∴ The mass of 41.2 mL of potassium bromide solution = (41,2 mL)(1.03 g) / (1.0 mL) = 42.436 g.

∴ The mass of potassium bromide in the solution = the mass of the solution x weight fraction of potassium bromide = (42.436 g) (0.083) = 3.52 g.