Question

calculate the mass of sodium sulphate required to prepare its 20% solution in 100g of water ​

Answer 1

Answer:

the mass of sodium sulphate required to prepare its 20% solution in 100g of water ​is 25 grams

Explanation:

Let the mass of sodium sulphate required be =xg

The mass of solution =(x+100)g

x g of solute in (x + 100) g of solution

20% =x/  x+100  ×100

20x+2000=100x

80x=2000

x=  2000 /80

​  =25 g

Answer 2

The mass by mass percentage of a solution is given by the following relation

mass by mass percentage = (mass of solute / mass of solution) × 100

where

mass of the solution = mass of solute + mass of

solvent

Here we are given that the mass percent of sodium sulphate solution is 20 %. Let the mass of sodium sulphate which is required to prepare this solution be 'a' grams. We are given that the mass of water is 100 g. So

20 = [a / (a + 100)] × 100

Solving for a, we get

a = 25g

Thus, 25g of sodium sulphate is required.

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