Respuesta :

Step 1

% by mass is defined as:

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

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

Step 2

The mass of the solution = mass of solute (KBr) + mass of solvent (water) = 123 g + 689 g = 812 g

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

Step 3

Procedure:

123 g KBr ------ 812 g solution

X ------ 100 g solution

X = 100 g solution x 123 g KBr/812 g solution = 15.1 g KBr = 15.1 % by mass

Answer: 15.1 % by mass