Question

What will be the mass percentage of a resulting solution prepared by mixing $15\%$ (w/w) 500 g aqueous solution of the area with $25\%$ (w/w) 400g aqueous solution of it?

• A. $18\%$
• B. $20\%$
• C. $25\%$
• D. $15\%$

Answer 1

The correct option is A $18\%$

Given $\left(w/w\right)\%$ of $1^{st}$ solution $=15$

$⟹15=\frac{500}{Weightofsolution\left(x_1\right)}\times 100$

$⟹x_1=\frac{\left(500\right)\left(100\right)}{15}$

$⟹x_1=\frac{{10}^4}{3}$

Given $\left(w/w\right)\%$ of $2^{nd}$ solution $=25$

$⟹25=\frac{400}{Weightofsolution\left(x_2\right)}\times 100$

$⟹x_2=\frac{\left(400\right)\left(100\right)}{25}$

$⟹x_2=1600$

Total $\left(w/w\right)\%=\left[\frac{500+400}{\frac{{10}^4}{3}+1600}\right]\times 100=\frac{900}{33.3+16}=\frac{900}{49.3}\simeq 18$

$\therefore$ Weight by weight percentage of resulting solution is $18\%$