Question

What is the percent by mass of 15 g NaCl dissolved in 85 g of water?

Answer 1

First, we need to understand what a solution is:

Solution = solute NaCl) + solvent (water)

% (m/m): mass of solute ----- 100 g of solution

Mass of solute = 15 g NaCl

Mass of solution = 15 g + 85 g = 100 g solution

Procedure:

15 g NaCl ------- 100 g Solution

X ------- 100 g Solution

In this case, there is a coincidence in numbers.

X = 15 g NaCl = 15 % (m/m)

Answer: 15 % (m/m)