Question

A solution contains 72.0 g of HCl and 468 g of (C6H6). What is the mole fraction of benzene?

Answer 1

Hello Dear.

Given ⇒
Mass of the HCl. = 72 grams.
Mass of the Benzene = 468 grams.

For HCl.
Molar Mass = 36.5 g/mole.
[∵ 1 + 35.5 = 36.5]

∵ No. of moles = Mass/Molar Mass
∴ No. of moles of HCl. = 72/36.5
    = 1.9

For Benzene, 
Molar Mass = 78 g/mole.
[∵ 12 × 6 + 1 × 6 = 78]

∴ No. of moles of Benzene = 468/78
    = 6 moles.


Total number of moles in a solution = No. of moles of HCl. + No. of moles of the Benzene.
= 1.9 + 6
= 7.9 moles. 


Using the Formula,
Mole Fraction of Benzene = No. of moles of Benzene/Total number of moles in a solution.
= 6/7.9
= 0.76


Hence, the moles fraction of the Benzene in a solution of Hydrogen Chloride and Benzene is 0.76



Hope it helps.

Answer 2

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• The mole fraction of benzene is 0.752.