Question

Q. 7.
A solution is obtained by mixing 300 g of 25% and 400 g of 40% solution by mass. Calculate the mass
percentage of the resulting solution.
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Answer 1

Mass of the solute (i) ⇒ $\sf 300\times \frac{25}{100}$

⇒ $\sf 3\times 25$

⇒ $\sf 75\ grams$

Mass of the solute (ii) ⇒ $\sf 400\times \frac{40}{100}$

⇒ $\sf 4\times 40$

⇒ $\sf 160 \ grams$

The total mass of the solutes ⇒ $\sf 75+160 = 235 \ grams$

The total mass of the solution ⇒ $\sf 300+400 = 700\ grams$

Percentage of composition by the mass of the solute⇒

$\sf \dfrac{Mass \ of \ Solute }{Total \ mass \ of \ Solution} \times 100$

⇒ $\sf \dfrac{235}{700} \times 100$

⇒ $\sf \dfrac{235}{7}$

⇒ $\sf 33.57 \%$

Percentage of composition by the mass of the solvent ⇒ $\sf 100-33.57$

⇒ $\sf 66.43\%$