What is the molality of a solution that contains 75.3 g of KCl dissolved in 95.0 g of water? (Molar mass of KCl = 74.55 g/mol)

• A. 10.6 mol/kg
• B. 1.06 mol/kg
• C. 7.95 mol/kg
• D. 0.795 mol/kg

Answer: (A)

Verified step by step guidance

1. Identify the given data: mass of KCl = 75.3 g, mass of water (solvent) = 95.0 g, and molar mass of KCl = 74.55 g/mol.
2. Calculate the number of moles of KCl using the formula: \(\text{moles of KCl} = \frac{\text{mass of KCl}}{\text{molar mass of KCl}} = \frac{75.3}{74.55}\).
3. Convert the mass of the solvent (water) from grams to kilograms because molality is expressed in moles of solute per kilogram of solvent: \$95.0 \text{ g} = 0.0950 \text{ kg}$.
4. Use the definition of molality: \(m = \frac{\text{moles of solute}}{\text{kilograms of solvent}}\) to set up the expression for molality.
5. Substitute the values calculated in steps 2 and 3 into the molality formula to find the molality of the KCl solution.