A solution is prepared by dissolving 0.50 mol of NaBr in enough water to make 1.0 L of solution. What is the molarity of Br⁻ in the solution?

• A. 0.50 M
• B. 0.25 M
• C. 2.0 M
• D. 1.0 M

Answer: (A)

Verified step by step guidance

1. Identify the species that dissociate in solution. Sodium bromide (NaBr) dissociates completely into Na⁺ and Br⁻ ions in water.
2. Write the dissociation equation: \(\text{NaBr} \rightarrow \text{Na}^+ + \text{Br}^-\).
3. Determine the moles of Br⁻ ions produced. Since 1 mole of NaBr produces 1 mole of Br⁻, the moles of Br⁻ will be equal to the moles of NaBr dissolved, which is 0.50 mol.
4. Calculate the molarity of Br⁻ ions using the formula for molarity: \(M = \frac{\text{moles of solute}}{\text{volume of solution in liters}}\).
5. Substitute the values: moles of Br⁻ = 0.50 mol, volume = 1.0 L, so \(M_{\text{Br}^-} = \frac{0.50}{1.0}\).