Question

Calculate the Mass of sodium sulphate required to prepare its 20%(mass percent) solution of 100g of water

Answer 1

Answer:

20

Explanation:

1. Na2So4 is solvent =?
2. Mass%= mass of solute*100 /total mass of solution
3. Mass of solute = mass%*mass of solution /100
4. Na2So4 = 20*100/100
5. =20

Answer 2

$\red{\bf{\underline{\underline{Correct\:Question:}}} }$

$<b>Calculate the Mass of sodium sulphate required to prepare its 20%(mass percent) solution of 100g of water ? </b>$

$\green{\bf{\underline{\underline{SOLUTION:}}}}$

Let,

The mass of sodium sulphate required be = $xg$

The mass of sodium would be = $(x + 100)g$

$xg$ of solute in $(x + 100)g$ of solution,

$⟹{{20}={\dfrac{x}{x+100}}×100}$

$⟹{2x + 2000} = {100x}$

$⟹{80x} = {2000x}$

$⟹ {x=\dfrac{\cancel{2000}}{\cancel{80}}=\bf{25g}}$

Hence, to prepare 20% solution in 100 gram of water 25 gram of sodium sulphate is needed.