Benzene contains only carbon and hydrogen and has a molar mass of 78.1 g/mol. Analysis shows the compound to be 7.44% hydrogen by mass. Find the empirical and molecular Formula of benzene.

Question

Chemistry

Jelly

28 December, 19:54

Benzene contains only carbon and hydrogen and has a molar mass of 78.1 g/mol. Analysis shows the compound to be 7.44% hydrogen by mass. Find the empirical and molecular Formula of benzene.

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Answers (1)

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Destiney · Answer 1

Hydrogen - 7.44%

Carbon - (100-7.44) % = 92.56%

Lets take 100 g of benzene, then we have

Hydrogen - 7.44 g

Carbon - 92.56 g

n - number of moles

n (H) = 7.44g * 1 mol/1.0g = 7.44 mol

n (C) = 92.56 g * 1mol/12.0 g ≈ 7.713 mol

n (C) : n (H) = 7.713 mol : 7.44 mol = 1:1

Empirical formula is CH.

M (CH) = (12.0 + 1.00) g/mol = 13.0 g/mol

M (benzene) = 78.1 g/mol

M (benzene) / M (CH) = 78.1 g/mol/13.0 g/mol = 6

So, molecular formula of benzene is C6H6.