Question

What quantity (in mL) of a $45\%$ acid solution of a monoprotic strong acid must be mixed with a $20\%$ solution of the same acid to produce $800\ mL$ of a $29.875\%$ acid solution ?

• A. 320
• B. 325
• C. 316
• D. 330

Answer 1

Answer: (C)

316

Answer 2

$\frac{V\times45}{100}+\frac{\left(800-V\right)20}{100}=\frac{800\times29.875}{100}$
$\frac{9V}{20}+160-\frac{V}{5}=239$
$\frac{5V}{20}=79$
$\Rightarrow V=316$