A solution has molarity 3 M and mass percent 12. The molar mass of solute is 40. What is the density of the solution?
Answer and explanation
Correct answer: 1.00 g mL−1
Consider 1 L of solution. A 3 M solution contains 3 mol solute in this volume, so solute mass = 3 × 40 = 120 g. Since this is 12% of the total solution mass, total mass = 120 ÷ 0.12 = 1000 g. Density is mass divided by volume: 1000 g ÷ 1000 mL = 1.00 g mL−1. Therefore option B is correct; confusing solute mass with solution mass would be incorrect.
Frequently asked questions
What is the correct answer to this question?
1.00 g mL−1
Why is this the correct answer?
Consider 1 L of solution. A 3 M solution contains 3 mol solute in this volume, so solute mass = 3 × 40 = 120 g. Since this is 12% of the total solution mass, total mass = 120 ÷ 0.12 = 1000 g. Density is mass divided by volume: 1000 g ÷ 1000 mL = 1.00 g mL−1. Therefore option B is correct; confusing solute mass with solution mass would be incorrect.
Which subject and chapter does this question cover?
This is a Class 11 Chemistry question. Chapter: Some Basic Concepts of Chemistry. Topic: Mole concept and molar mass.
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