What is the approximate mass percentage of sodium chloride in a 1.0 molal sodium chloride solution? Molar mass is 58.5 g per mol.
Answer and explanation
Correct answer: 5.53 percent
A 1.0 molal solution contains 1 mol NaCl in 1 kg water. The solute mass is 58.5 g, and total solution mass is 1000 + 58.5 = 1058.5 g. Mass percentage = (58.5/1058.5) × 100 = 5.53% approximately. The solute must be included in the total mass; using 1000 g as denominator would give an incorrect value.
Frequently asked questions
What is the correct answer to this question?
5.53 percent
Why is this the correct answer?
A 1.0 molal solution contains 1 mol NaCl in 1 kg water. The solute mass is 58.5 g, and total solution mass is 1000 + 58.5 = 1058.5 g. Mass percentage = (58.5/1058.5) × 100 = 5.53% approximately. The solute must be included in the total mass; using 1000 g as denominator would give an incorrect value.
Which subject and chapter does this question cover?
This is a Class 11 Chemistry question. Chapter: Chapter 01: Solutions.
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