Question

What is the molarity of a solution prepared by dissolving 8.0 g of NaOH in enough water to make 2.0 L of solution? (Molar mass of NaOH = 40 g/mol)

• A. \( 0.10 \, \text{M} \)
• B. \( 0.15 \, \text{M} \)
• C. \( 0.20 \, \text{M} \)
• D. \( 0.25 \, \text{M} \)

Hint:

To find molarity, divide the number of moles of solute by the volume of the solution in liters.

Answer 1

The Correct Option is A

First, calculate the number of moles of NaOH: \[ \text{Moles of NaOH} = \frac{\text{Mass}}{\text{Molar mass}} = \frac{8.0 \, \text{g}}{40 \, \text{g/mol}} = 0.2 \, \text{mol} \] Next, calculate the molarity of the solution using the formula: \[ \text{Molarity} = \frac{\text{Moles of solute}}{\text{Volume of solution in liters}} = \frac{0.2 \, \text{mol}}{2.0 \, \text{L}} = 0.10 \, \text{M} \] Thus, the molarity of the solution is \( 0.10 \, \text{M} \).