Organic Chemistry
What's covered
Key facts
Alcohols
All alcohols contain the functional group –OH (hydroxyl group), which gives the homologous series its shared chemical properties.
Alkanes
Equivalent written form: CnH(2n+2) / CₙH₂ₙ₊₂.
Alkenes
Addition polymerisation is when many alkene monomers join to form a polymer.
Carboxylic Acids
The functional group of all carboxylic acids is the carboxyl group, written –COOH.
Combustion
Carbon monoxide is dangerous because it binds tightly to haemoglobin in red blood cells, blocking oxygen transport and causing potentially fatal poisoning.
Cracking
Alkenes from cracking are used to make polymers.
Ethanol
Ethanol can be produced by the fermentation of glucose using yeast in the absence of oxygen (anaerobic respiration).
Naming Hydrocarbons
Alcohols are named with the suffix -ol; their functional group is –OH (e.g. methanol, ethanol).
Polymers
In addition polymerisation, each monomer's double bond opens to form a new single bond joining monomers.
Alcohols
The first four alcohols in the homologous series are methanol, ethanol, propanol and butanol.
Sample questions
A taste of the 93 questions in this topic, answers marked. Sign up to practise the full set with spaced repetition.
What are the first four alcohols in the homologous series, in order?
- •Methanal, ethanal, propanal, butanal
- •Methane, ethane, propane, butane
- ✓Methanol, ethanol, propanol, butanol
- •Methene, ethene, propene, butene
What is the first alkane in the series?
- •Ethane (C₂H₆)
- •Ethene (C₂H₄)
- ✓Methane (CH₄)
- •Methanol (CH₃OH)
What is the test for an alkene?
- •Alkenes always burn with a smokier yellow flame than alkanes
- ✓Bromine water decolorises (orange → colourless) as it adds across C=C
- •Sodium added to the sample fizzes vigorously, releasing hydrogen
- •Universal indicator turns blue/purple because alkenes are slightly basic
Why does a carboxylic acid have a higher pH than a strong acid of the same concentration?
- •All of its molecules ionise fully in water
- •It contains fewer hydrogen atoms overall
- •It is more dilute than the strong acid
- ✓Only a small fraction of its molecules ionise
What are the products of complete combustion of a hydrocarbon fuel?
- •Carbon and water
- •Carbon dioxide and hydrogen
- ✓Carbon dioxide and water
- •Carbon monoxide and water
What is cracking?
- ✓Breaking long alkanes into short alkanes and alkenes, matching supply to demand
- •Joining short alkanes into longer, higher-boiling fuels for industrial use
- •Removing sulfur from crude oil to reduce acid rain when fuel is burnt
- •Separating crude oil fractions by boiling point in a distillation column
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