How many milliliters of a 25% (m/v) NaOH solution are required to obtain 75 g of NaOH?

• A. 25 mL
• B. 300 mL
• C. 75 mL
• D. 375 mL

Answer: (B)

Verified step by step guidance

1. Understand that a 25% (m/v) NaOH solution means there are 25 grams of NaOH in every 100 mL of solution.
2. Set up a proportion to find the volume of solution needed to get 75 grams of NaOH: if 25 g is in 100 mL, then 75 g will be in x mL.
3. Write the proportion as \(\frac{25\ \text{g}}{100\ \text{mL}} = \frac{75\ \text{g}}{x\ \text{mL}}\).
4. Solve for \(x\) by cross-multiplying: \$25 \times x = 75 \times 100$.
5. Isolate \(x\) by dividing both sides by 25: \(x = \frac{75 \times 100}{25}\), which gives the volume in milliliters needed.