Complete combustion of a compound containing hydrogen and carbon produced 2.641 g of carbon dioxide and 1.442 grams of water as the only products. the molar mass of the hydrocarbon is 88.1 g/mol. what are the empirical and molecular formulas?

Question

Chemistry

Jeffery Galvan

11 April, 04:59

Complete combustion of a compound containing hydrogen and carbon produced 2.641 g of carbon dioxide and 1.442 grams of water as the only products. the molar mass of the hydrocarbon is 88.1 g/mol. what are the empirical and molecular formulas?

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Answers (1)

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Lucille Eaton · Answer 1

1) Answer is: the empirical formula of the hydrocarbon is C₃H₈.

Chemical reaction: CₓHₐ + O₂ → xC + a/2H₂O.

m (CO₂) = 2.641 g.; mass of carbon dioxide.

n (CO₂) = m (CO₂) : M (CO₂).

n (CO₂) = 2.641 g : 44.01 g/mol.

n (CO₂) = n (C) = 0.06 mol; amount of carbon.

m (H₂O) = 1.442 g.

n (H₂O) = 1.442 g : 18 g/mol.

n (H₂O) = 0.08 mol.

n (H) = 2 · n (H₂O) = 0.16 mol; amount of hydrogen.

n (C) : n (H) = 0.06 mol : 0.16 mol / 0.06 mol.

n (C) : n (H) = 1 : 2. 67 / *3.

n (C) : n (H) = 3 : 8.

2) Answer is: the molecular formula of hydrocarbon is C₆H₁₆.

M (C₃H₈) = 44.05 g/mol; molar mass of empirical formula.

M (CₓHₐ) = 88.1 g/mol; molar mass of hydrocarbon.

M (CₓHₐ) : M (C₃H₈) = 88.1 g/mol : 44.05 g/mol.

M (CₓHₐ) : M (C₃H₈) = 2.

The molar mass of hydrocarbon is two times higher than molar mass of empirical formula, so number of carbon atoms is six and number of hydrogen atoms sixteen.