Question

What is the percent mass of 37.5 g NaCl dissolved in 137.5 g water?

Answer 1

Step 1

% by mass is defined as:

mass of solute ----- 100 g of solution

Solution = solute + solvent

Solute = NaCl

Solvent = Water (H2O)

----------------------------------------------

Step 2

Mass of solution = 37.5 g (NaCl) + 137.5 g (water) = 175 g

----------------------------------------------

Step 3

Procedure:

37.5 g NaCl ----- 175 g solution

X ----- 100 g solution

X = 100 g solution x 37.5 g NaCl/175 g solution = 21.4 g NaCl = 21.4 % by mass

Answer: % by mass = 21.4 %