Question

20 mL of a 20% w/w Solution of density 1.1 g / mL is diluted until its concentration becomes 4% w/w. Determine the mass of water added.

Answer 1

In dilution solvent is added and mass of solute is constant. 

Let w g of water is added. 

(20 x 1.1) x 20 /100 = (20 x 1.1+ w) x 4/100 or W = 88 g