If 10 grams of NaCl is dissolved in enough water to make 500 mL of solution, wha

If 10 grams of NaCl is dissolved in enough water to make 500 mL of solution, what is the molality of the solution? (Molar mass of NaCl = 58.5 g/mol)

If 10 grams of NaCl is dissolved in enough water to make 500 mL of solution, what is the molality of the solution? (Molar mass of NaCl = 58.5 g/mol)

Step 1: Identify the mass of NaCl given, which is 10 grams.
Step 2: Find the molar mass of NaCl, which is 58.5 g/mol.
Step 3: Calculate the number of moles of NaCl using the formula: moles = mass (g) / molar mass (g/mol). So, moles of NaCl = 10 g / 58.5 g/mol.
Step 4: Perform the calculation: 10 g / 58.5 g/mol = 0.171 moles of NaCl.
Step 5: Determine the volume of the solution, which is 500 mL. Convert this to kilograms of water (solvent). Since 1 L of water is approximately 1 kg, 500 mL = 0.5 kg.
Step 6: Use the formula for molality (m), which is moles of solute / kg of solvent. Here, m = 0.171 moles / 0.5 kg.
Step 7: Perform the calculation: 0.171 moles / 0.5 kg = 0.34 m.

Molarity vs. Molality – Understanding the difference between molarity (moles of solute per liter of solution) and molality (moles of solute per kilogram of solvent) is crucial for solving this problem.
Calculating Moles – The ability to convert grams of a substance to moles using its molar mass is a fundamental skill in chemistry.
Mass of Solvent – Recognizing that molality requires the mass of the solvent (water) in kilograms, not the total volume of the solution.