Question

To prepare 100 g of a 20% by weight solution of NaOH, the weight of H₂O needed is ???​

Answer 1

Answer:

80 g

Explanation:

Answer 2

Thus the mass of water is 80 grams.

Given:

100 g of a 20% by weight solution of NaOH.

To find:

The weight of water needed.

Solution:

In the solution of NaOH and water, NaOH is the solute and water is the solvent.

The concentration of NaOH solution is 20%.

So, we can write-

Concentration=mass of solute/total mass of solution ×100.

The mass of NaOH=x.

Mass of the solution=100 grams.

$20 = \frac{x}{100} \times 100 \\ x = 20$

Thus the mass of NaOH is 20 grams so, the mass of water is 100-20=80 grams.

Thus the mass of water is 80 grams.