50 mL of a 0.5 mol L^-1 solution contains 0.025 mol solute. If it is concentrated by evaporation to 25 mL, what will be the molarity?
Answer and explanation
Correct answer: 1.00 mol L^-1
Evaporation removes solvent, so the stated 0.025 mol solute remains unchanged, assuming no solute is lost. The final volume is 25 mL = 0.025 L. Therefore molarity = 0.025/0.025 = 1.00 mol L^-1. Since the volume is reduced to half while moles remain constant, the original molarity doubles from 0.5 to 1.0 mol L^-1.
Frequently asked questions
What is the correct answer to this question?
1.00 mol L^-1
Why is this the correct answer?
Evaporation removes solvent, so the stated 0.025 mol solute remains unchanged, assuming no solute is lost. The final volume is 25 mL = 0.025 L. Therefore molarity = 0.025/0.025 = 1.00 mol L^-1. Since the volume is reduced to half while moles remain constant, the original molarity doubles from 0.5 to 1.0 mol L^-1.
Which subject and chapter does this question cover?
This is a Class 11 Chemistry question. Chapter: Chapter 01: Solutions.
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