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

Provided Information:

• Mass of NaOH: 10 g
• Molar Mass of NaOH: 40 g/mol
• Solution Volume: 250 mL (equivalent to 0.250 L)

Step 1: Determine the Moles of NaOH

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

Step 2: Compute the Molarity

Molarity (M) = \( \frac{\text{Moles of Solute}}{\text{Volume of Solution (L)}} \)

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

✅ Conclusion:

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