Question

How many grams of a 25% by mass solution of KOH should be added to 400 ml of water to prepare a 15% by mass solution?

• A. 200 g
• B. 400 g
• C. 800 g
• D. 600 g

Answer 1

The correct option is D 600 g

Let x g of 25% KOH be added to 400 ml $H_{2}O$, then
$\frac{x\times 0.25}{x+400}=0.15\Rightarrow x=\frac{0.15\times 400}{0.1}=600g$