Question

What is the molarity of a solution prepared by dissolving 10 grams of NaOH in 250 mL of water? (Molar mass of NaOH = 40 g/mol)

• A. 1 M
• B. 0.5 M
• C. 0.1 M
• D. 2.0 M

Hint:

To find the molarity, use the formula: \(\text{Molarity} = \frac{\text{moles of solute}}{\text{volume in liters}}\).

Answer 1

The Correct Option is A

Given:

• Mass of NaOH = 10 g
• Molar mass of NaOH = 40 g/mol
• Volume of solution = 250 mL = 0.250 L

Step 1: Calculate the number of moles of NaOH

Moles of NaOH = \( \frac{\text{Mass}}{\text{Molar Mass}} = \frac{10 \, \text{g}}{40 \, \text{g/mol}} = 0.25 \, \text{mol}

Step 2: Calculate the molarity of the solution

Molarity \( M \) = \( \frac{\text{moles of solute}}{\text{volume of solution in liters}} \)

\(M =  \frac{0.25 \, \text{mol}}{0.250 \, \text{L}} = 1.0 \, \text{M} \)

✅ Final Answer:

The molarity of the solution is \( \boxed{1.0 \, \text{M}} \)