# Formulae of organic compounds

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• Created by: racheon
• Created on: 15-04-14 17:09
Define empirical formula.
The simplest whole-number ratio of atoms of each elements present in a compound.
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A hydrocarbon was found to contain 85.63% carbon and 14.37% hydrogen. Calculate its empirical formula.
100g contains 85.63g of C and 14.37g of H. 1: Find the molar ratio-C-85.63÷12=7.14:H-14.37÷1=14.37. 2: Divide by smallest number-1:2. Empirical formula=CH₂.
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Define molecular formula.
The actual number of atoms of each element in a molecule.
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A compound has an empirical formula of CH₂O and a relative molecular mass of 60. Find its molecular formula.
1: Find the relative empirical mass of the empirical formula-CH₂O=12+1+1+16=30. 2: Divide the relative molecular mass by the relative empirical mass-60÷30=2. The molecular formula is twice the empirical formula, C₂H₄O₂.
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Define general formula.
The simplest algebraic formula of a member of a homologous series.
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Define displayed formula.
It shows the relative positioning of all the atoms in a molecule and the bonds between them.
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How do you work out amount, n?
mass, m÷molar mass, M.
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What must you show when doing questions about formulae?
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What must you remember to draw when drawing displayed formulae?
All the atoms and bonds, even those between the oxygen and hydrogen in an alcohol group.
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## Other cards in this set

### Card 2

#### Front

A hydrocarbon was found to contain 85.63% carbon and 14.37% hydrogen. Calculate its empirical formula.

#### Back

100g contains 85.63g of C and 14.37g of H. 1: Find the molar ratio-C-85.63÷12=7.14:H-14.37÷1=14.37. 2: Divide by smallest number-1:2. Empirical formula=CH₂.

### Card 3

#### Front

Define molecular formula.

### Card 4

#### Front

A compound has an empirical formula of CH₂O and a relative molecular mass of 60. Find its molecular formula.

### Card 5

#### Front

Define general formula.