If a 0.2 m solution is prepared using 0.5 kg of solvent, how many moles of solute are present?
Answer and explanation
Correct answer: 0.10 mol
Molality is defined as m = moles of solute divided by kilograms of solvent. Rearranging gives moles of solute = molality × mass of solvent in kilograms. Thus, n = 0.2 mol kg⁻¹ × 0.5 kg = 0.10 mol. Therefore, option B is correct. The mass used in this formula is the mass of solvent, not the total mass of the solution, and it must be expressed in kilograms.
Frequently asked questions
What is the correct answer to this question?
0.10 mol
Why is this the correct answer?
Molality is defined as m = moles of solute divided by kilograms of solvent. Rearranging gives moles of solute = molality × mass of solvent in kilograms. Thus, n = 0.2 mol kg⁻¹ × 0.5 kg = 0.10 mol. Therefore, option B is correct. The mass used in this formula is the mass of solvent, not the total mass of the solution, and it must be expressed in kilograms.
Which subject and chapter does this question cover?
This is a Class 12 Chemistry question. Chapter: Chapter 01: Solutions. Topic: 5: Colligative Properties.
Student feedback
Was this question useful?
👍 0 Helpful 👎 0 Not helpful
Yes 0% No 0%
0 responsesStudent Reviews
No published reviews yet.
