What is the mole fraction of benzene in a mixture of 39 g benzene and 46 g toluene?
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Answer and explanation
Correct answer: 0.50
Benzene has molar mass about 78 g mol−1, so 39 g is 0.5 mol. Toluene has molar mass about 92 g mol−1, so 46 g is also 0.5 mol. Total moles are 1.0 mol, and benzene mole fraction is 0.5/1.0 = 0.50. Therefore C is correct; equal masses happen to give equal moles here because the masses are proportional to molar masses.
Frequently asked questions
What is the correct answer to this question?
0.50
Why is this the correct answer?
Benzene has molar mass about 78 g mol−1, so 39 g is 0.5 mol. Toluene has molar mass about 92 g mol−1, so 46 g is also 0.5 mol. Total moles are 1.0 mol, and benzene mole fraction is 0.5/1.0 = 0.50. Therefore C is correct; equal masses happen to give equal moles here because the masses are proportional to molar masses.
Which subject and chapter does this question cover?
This is a Class 11 Chemistry question. Chapter: Chapter 01: Solutions.
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