Question

A solution is made containing 4.6g of potassium chloride per 64.0g of water. What is the weight/weight % or percent by mass of the solute?

Answer 1

The w/w% of KCl in the solution is 6.7%.

Explanation:

The weight/weight percent of a solute in solution is determined by dividing the mass of the solute by the total mass of the solution, which is the sum of the mass of the solute and the mass of the solvent.

`"mass of solute"/"mass of solution"xx100="w/w%"`

In this problem, the mass of the solute potassium chloride is 4.6 g. The mass of the solvent (water) is 64.0 g.

The mass of the solution is `4.6 "g KCl"+64.0 "g H"_2"O"=68.6 "g solution"`

Calculate the w/w% of KCl in the solution.

`(4.6"g KCl")/(68.6 "g solution")xx100=6.7 "w/w% KCl"` (rounded to two significant figures)