18 g of glucose is dissolved in 200 g of water. What will be the molality of the solution?
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Answer and explanation
Correct answer: 0.50 mol kg−1
Molality uses moles of solute per kilogram of solvent. Glucose moles are 18/180 = 0.10 mol, and 200 g water equals 0.200 kg. Therefore molality = 0.10/0.200 = 0.50 mol kg−1. Option B is correct. The denominator is the solvent mass, not the total solution mass, and it must be expressed in kilograms.
Frequently asked questions
What is the correct answer to this question?
0.50 mol kg−1
Why is this the correct answer?
Molality uses moles of solute per kilogram of solvent. Glucose moles are 18/180 = 0.10 mol, and 200 g water equals 0.200 kg. Therefore molality = 0.10/0.200 = 0.50 mol kg−1. Option B is correct. The denominator is the solvent mass, not the total solution mass, and it must be expressed in kilograms.
Which subject and chapter does this question cover?
This is a Class 11 Chemistry question. Chapter: Chapter 01: Solutions.
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