If molarity is to be kept the same and the volume of solution is doubled, what change is needed in moles of solute?
Answer and explanation
Correct answer: Moles must also be doubled
Molarity is the ratio M = n/V. If the volume is doubled while the amount of solute remains unchanged, the molarity becomes one-half of its original value. To keep M constant, the numerator must increase in the same proportion as the denominator. Therefore, when the solution volume doubles, the moles of solute must also double. Option A is correct; halving or leaving the moles unchanged would reduce molarity.
Frequently asked questions
What is the correct answer to this question?
Moles must also be doubled
Why is this the correct answer?
Molarity is the ratio M = n/V. If the volume is doubled while the amount of solute remains unchanged, the molarity becomes one-half of its original value. To keep M constant, the numerator must increase in the same proportion as the denominator. Therefore, when the solution volume doubles, the moles of solute must also double. Option A is correct; halving or leaving the moles unchanged would reduce molarity.
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.
