A solution contains 40 g of common salt in 320 g of water. Calculate the concentration in terms of mass by mass percentage of the solution.

Solution:
Mass of solute (salt) = 40 g
Mass of solvent (water) = 320 g
We know,
Mass of solution = Mass of solute +
Mass of solvent
= 40 g + 320 g
= 360 g
Mass percentage of solution
= Mass of solute / Mass of solution ×100

= 40/ 360 ×100 =11.1%