chemistry class

Question

A solution of CaCl2 in water forms a mixture that is 30.0% calcium chloride by mass. If the total mass of the mixture is 455.1 g, what masses of CaCl2 and water were used?

Answer 1

If there is 30% (by mass) of CaCl₂ in a 455.1g solution, then:

(455.1 g)(0.30) = 136.5 g CaCl₂

If 136.5 g of the mixture is CaCl2, then the remaining mass must be water:

455.1g – 136.5 g = 318.5 g H₂O

There is slight rounding in this answer, so be careful of how precise your teacher wants your answers.