Question

40gm of a salt is completely dissolved in water such that the concentration is 5%(w/w). Find the mass of water in the solution.​

Answer 1

Mass of common salt (solute)=40 g

Mass of water (soluted) =320 g

mass of solution=320+40=360 g

concentration of solution=

M(mass) of solute÷mass of solution×100

40/360×100=11.11%

Hence, the concentration of the solution is 11.11%

Answer 2

Let the mass of solvent (water) be x g.

Mass of solute (salt) = 40 g

∴Total mass of the solution = (x+40) g  

Now, concentration of the solution = 5 %( w/w)

∴ 40/(x+40) = 5/100

⇒ x+40 = 800

⇒ x = 760

Thus, the mass of water in the solution = 760g

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