Question

What mass of water should be added to 22.0 g of KCl to make

a 5.50 % by mass solution?_ gH20
Enter the answer

Answer 1

The correct answer is 378 g of water

Step-by-step explanation:

A concentration of 5.50% by mass means that there are 5.50 grams of solute in 100 grams of solution:

5.50 %m/m = 5.50 g solute/100 g solution

If we have 22.0 g of solute (KCl), we found the total mass of solution as follows:

5.50 g KCl ----- 100 g solution

22.0 g KCl ------ X = 22.0 g KCl x 100 g solution/ 5.50 g KCl = 400 g solution

22.0 g KCl/400 g solution = 5.5 g KCl/100 g solution = 5.50 % m/m

This is the total mass of solution (400 g). The mass of water we have to add is the following:

Mass water = 400.0 g solution - 22.0 g KCl = 378.0 g

So, in order to prepare a 5.50% m/m of solution, we have to weight 22.0 g of KCl and to add 378.0 g of water until reaching 400.0 g of total mass solution.