A solution has solute mole fraction 0.25. If molar masses of solute and solvent are 60 g mol−1 and 18 g mol−1 respectively, what is the approximate mass percentage of solute?
Answer and explanation
Correct answer: 52.6 percent
Use a one-mole solution basis. A solute mole fraction of 0.25 means 0.25 mol solute and 0.75 mol solvent. Their masses are 0.25 × 60 = 15 g and 0.75 × 18 = 13.5 g, giving 28.5 g total. The solute mass percentage is (15/28.5) × 100 = 52.63%, approximately 52.6%; therefore option C is correct.
Frequently asked questions
What is the correct answer to this question?
52.6 percent
Why is this the correct answer?
Use a one-mole solution basis. A solute mole fraction of 0.25 means 0.25 mol solute and 0.75 mol solvent. Their masses are 0.25 × 60 = 15 g and 0.75 × 18 = 13.5 g, giving 28.5 g total. The solute mass percentage is (15/28.5) × 100 = 52.63%, approximately 52.6%; therefore option C is correct.
Which subject and chapter does this question cover?
This is a Class 11 Chemistry question. Chapter: Some Basic Concepts of Chemistry. Topic: Percentage composition and empirical/molecular formulas.
