A solution contains 72.0 g of HClHCl and 468 g of C_6H_6C6H6. What is the mole fraction of benzene?

1 Answer
Meave60
Sep 15, 2016

The mole fraction of benzene is 0.752.

Explanation:

The mole fraction of a substance in a solution is equal to the moles of the substance divided by the total moles of all substances in the solution.

"Mole fraction"Mole fraction=="mol X"/"mol X+mol Y"mol Xmol X+mol Y

The mass of each compound needs to be converted to moles by dividing the mass by its molar mass.

First determine the molar mass of both compounds.

Molar Mass HCl:

(1xx1.008 "g/mol")+(1xx35.45 "g/mol")="36.458 g/mol"(1×1.008g/mol)+(1×35.45g/mol)=36.458 g/mol

Molar Mass "C"_6"H"_6"C6H6:

(6xx12.011"g/mol")+(6xx1.008"g/mol")="78.114 g/mol"(6×12.011g/mol)+(6×1.008g/mol)=78.114 g/mol

Next determine the moles present for each compound by dividing the mass given in the question by its molar mass.

Moles HCl:

"72.0 g HCl"xx"1 mol HCl"/"36.458 g HCl"="1.974 mol HCl"72.0 g HCl×1 mol HCl36.458 g HCl=1.974 mol HCl

Moles "C"_6"H"_6":C6H6:

"468 g C"_6"H"_6xx("1 mol C"_6"H"_6)/("78.114 g C"_6"H"_6)="5.991 mol C"_6"H"_6"468 g C6H6×1 mol C6H678.114 g C6H6=5.991 mol C6H6

Determine the Mole Fraction of Benzene

"C"_6"H"_6"C6H6rArr⇒"5.991"/"5.991+1.974"="0.752"5.9915.991+1.974=0.752

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