Question

An aqueous solution of copper sulphate was left in the hot sun. The heat caused some of the water to evaporate from the solution. The original 150g solution had concentration of 10% by mass. If the remaining solution has a concentration of 15% by mass, what volume of water was evaporated? tell me the steps of solving and not only the answer........

Answer 1

It had 150 g of water with 10% concentration means the mas of copper sulpahte in solution is 15 g.Then if it was 15% concentrated after evaporation it means that 15% of x(let) grams was 15 g. value of x is 100 g.Now 

Initial mass - final mass = evaporated mass of water 
150 - 100= 50 g. 

50 g of water = 50 ml. 

Keep this in mind: 

1 ml = 1 gm 
1 kg = 1 L