Question

What is the volume of solution needed to prepare a 3 Molarity (M) solution containing 80 g of NaOH?

• A. 1.50 L / 1500 mL
• B. 1.33 L / 1330 mL
• C. 0.67 L / 667 mL
• D. 0.50 L / 500 mL

Hint:

To calculate the volume of solution needed for a given molarity, always use the molarity formula $M = \frac{\text{moles}}{V}$ and convert mass to moles using the molar mass.

Answer 1

The Correct Option is C

Step 1: Molarity Formula
Use the molarity formula: \[ M = \frac{\text{moles of solute}}{\text{volume of solution in liters}} \] Step 2: Calculate NaOH moles
NaOH molar mass: \[ \text{Molar mass of NaOH} = 23 + 16 + 1 = 40 \, \text{g/mol} \] Moles of NaOH in 80 g: \[ \text{moles of NaOH} = \frac{80 \, \text{g}}{40 \, \text{g/mol}} = 2 \, \text{moles} \] Step 3: Find Volume using Molarity
Substitute values into the molarity formula: \[ 3 \, \text{M} = \frac{2 \, \text{moles}}{V} \] Solve for \(V\): \[ V = \frac{2 \, \text{moles}}{3 \, \text{M}} = 0.6667 \, \text{L} = 0.67 \, \text{L} = 667 \, \text{mL} \] Step 4: Conclusion
Required solution volume: 0.67 L (or 667 mL). \[ \boxed{0.67 \, \text{L} \, \text{or} \, 667 \, \text{mL} \, \text{is the required volume.}} \]