If molality is to be kept the same and mass of solvent is tripled, what change is needed in moles of solute?
Answer and explanation
Correct answer: Moles must be tripled
Molality is defined as moles of solute per kilogram of solvent: m = n divided by the solvent mass. If the solvent mass becomes three times larger and solute moles stay fixed, the molality becomes one-third. To preserve the original ratio, the solute amount must increase by the same factor. Thus, tripling the solvent mass requires tripling the solute moles, making option A correct.
Frequently asked questions
What is the correct answer to this question?
Moles must be tripled
Why is this the correct answer?
Molality is defined as moles of solute per kilogram of solvent: m = n divided by the solvent mass. If the solvent mass becomes three times larger and solute moles stay fixed, the molality becomes one-third. To preserve the original ratio, the solute amount must increase by the same factor. Thus, tripling the solvent mass requires tripling the solute moles, making option A correct.
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.
