In a solution, mole fractions of solute and solvent are equal. If molar masses of solute and solvent are 60 g per mol and 18 g per mol respectively, what is the approximate mass percentage of solute?
Answer and explanation
Correct answer: 76.9 percent
Equal mole fractions mean equal numbers of moles, so choose 1 mol of each component. Their masses are 60 g solute and 18 g solvent, giving a total of 78 g. Solute mass percentage = (60/78) × 100 = 76.92%, approximately 76.9%. Equal mole fractions do not imply equal masses because the molar masses differ.
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What is the correct answer to this question?
76.9 percent
Why is this the correct answer?
Equal mole fractions mean equal numbers of moles, so choose 1 mol of each component. Their masses are 60 g solute and 18 g solvent, giving a total of 78 g. Solute mass percentage = (60/78) × 100 = 76.92%, approximately 76.9%. Equal mole fractions do not imply equal masses because the molar masses differ.
Which subject and chapter does this question cover?
This is a Class 11 Chemistry question. Chapter: Chapter 01: Solutions.
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