A 10% by mass urea solution is made in water. What is the approximate mole fraction of water?
Advertisement
Answer and explanation
Correct answer: 0.968
Take 100 g solution: it contains 10 g urea and 90 g water. Urea moles are 10/60 = 0.1667 mol, while water moles are 90/18 = 5.00 mol. Total moles are 5.1667, so Xwater = 5.00/5.1667 = 0.9677, approximately 0.968. Thus C is correct; mass percentage itself is not the mole fraction.
Frequently asked questions
What is the correct answer to this question?
0.968
Why is this the correct answer?
Take 100 g solution: it contains 10 g urea and 90 g water. Urea moles are 10/60 = 0.1667 mol, while water moles are 90/18 = 5.00 mol. Total moles are 5.1667, so Xwater = 5.00/5.1667 = 0.9677, approximately 0.968. Thus C is correct; mass percentage itself is not the mole fraction.
Which subject and chapter does this question cover?
This is a Class 11 Chemistry question. Chapter: Chapter 01: Solutions.
Advertisement