Carbon-based compounds: from fuels to polymers.
A finite resource found in rocks. It is a mixture of many compounds, mostly hydrocarbons (compounds containing ONLY carbon and hydrogen).
Oil is heated until it evaporates. The column is hot at the bottom and cool at the top. Fractions condense at different levels based on their boiling points.
| Chain Length | Boiling Point | Viscosity (Thickness) | Flammability |
|---|---|---|---|
| Short (Top) | Low | Low (Runny) | High |
| Long (Bottom) | High | High (Thick) | Low |
Alkanes are saturated hydrocarbons—they only have single C-C bonds. This means they contain as many Hydrogen atoms as possible.
General Formula: $$ C_nH_{2n+2} $$
Mnemonic: Mice Eat Paper Bags (Meth-, Eth-, Prop-, But-)
Q1: What is the formula for an alkane with 5 Carbon atoms (Pentane)?
$$ C_5H_{(2 \times 5) + 2} = C_5H_{12} $$
Alkenes are unsaturated because they contain at least one double C=C bond. They are much more reactive than alkanes.
General Formula: $$ C_nH_{2n} $$
Breaking down long-chain hydrocarbons into smaller, more useful ones (short-chain alkane + alkene). This requires a catalyst and heat.
Q1: How do you test for an alkene?
Add Bromine Water. It will turn from orange/brown to colourless if an alkene is present.
These are homologous series with specific groups of atoms that determine their reactions.
| Series | Functional Group | Naming Suffix | Example |
|---|---|---|---|
| Alcohols | -OH | -ol | Ethanol ($CH_3CH_2OH$) |
| Carboxylic Acids | -COOH | -oic acid | Ethanoic acid ($CH_3COOH$) |
| Esters | -COO- | -oate | Ethyl ethanoate |
In Ethanoic acid, the C=O and -OH are on the same carbon. Don't forget the double bond!
Occurs when many small alkenes (monomers) join together. The double bond opens up to form a long chain.
Involves monomers with two functional groups. When they react, they join together and lose a small molecule, usually water ($H_2O$).
Q1: What is the main difference between addition and condensation polymerisation?
Addition uses one monomer (alkene) and produces only the polymer. Condensation uses two different monomers and produces the polymer plus a small molecule like water.
1. Don't say hydrocarbons contain "carbon, hydrogen, and oxygen"; they ONLY contain C and H.
2. Don't forget that Alkenes turn bromine water colourless, not clear.
3. Don't confuse Alkane ($C_nH_{2n+2}$) and Alkene ($C_nH_{2n}$) formulas in calculations.
4. Don't forget that every Carbon atom must have exactly 4 bonds in your drawings.