Question:
A solution is obtained by mixing 300 g of 25% solution and 400 g of 40% solution by mass. Calculate the mass percentage of the resulting solution.
Solution:
Total amount of solute present in the mixture is given by,
$300 \times \frac{25}{100}+400 \times \frac{40}{100}$
= 75 + 160
= 235 g
Total amount of solution = 300 + 400 = 700 g
Therefore, mass percentage $(w / w)$ of the solute in the resulting solution, $=\frac{235}{700} \times 100 \%$
= 33.57%
And, mass percentage (w/w) of the solvent in the resulting solution,
= (100 − 33.57)%
= 66.43%