If the molality is 0.2 m and the mass of solvent is 0.25 kg, how many moles of solute are present?
Advertisement
Answer and explanation
Correct answer: 0.050 mol
Molality is defined as the moles of solute divided by the mass of solvent in kilograms: m = nsolute ÷ mass of solvent. Rearranging gives nsolute = m × mass of solvent. Therefore, nsolute = 0.2 mol kg⁻¹ × 0.25 kg = 0.050 mol. The kilogram units cancel, leaving mol. Thus, option B is correct.
Frequently asked questions
What is the correct answer to this question?
0.050 mol
Why is this the correct answer?
Molality is defined as the moles of solute divided by the mass of solvent in kilograms: m = nsolute ÷ mass of solvent. Rearranging gives nsolute = m × mass of solvent. Therefore, nsolute = 0.2 mol kg⁻¹ × 0.25 kg = 0.050 mol. The kilogram units cancel, leaving mol. Thus, option B is correct.
Which subject and chapter does this question cover?
This is a Class 12 Chemistry question. Chapter: Chapter 01: Solutions. Topic: 2: Concentration Metrics.
Advertisement