Apotassium 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

3.52 g.

Explanation:

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.

i think 4.44 moles