4. organic chemistry

Hydrocarbon

A chemical compound composed of carbon and hydrogen ONLY.

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As the chain of a hydrocarbon gets longer what happens to intermolecular forces, viscosity and boiling point?

As the hydrocarbon chain gets longer the intermolecular forces increase

As the hydrocarbon chain gets longer the viscosity increases

As the hydrocarbon chain gets longer the boiling point increases

Fractional Distillation

A separation technique used to separate a mixture of liquids into different fractions by their boiling point.

Order of Fractions in Fractionating Column

From top to bottom: Refinery gases, gasoline, kerosene, diesel oil, fuel oil, bitumen.

Trend in Boiling Point and Hydrocarbon Chain Length

Boiling points get HIGHER and hydrocarbon chain length gets LONGER as you go down the column.

Boiling Point

The temperature at which a liquid turns into a gas.

Volatility

How easily something evaporates.

Viscosity

How easily something flows.

Flammability

How easily something burns.

Alkane

A group of saturated hydrocarbons.

General Formula for an Alkane

CnH2n+2.

Mnemonic for Naming Order of First 4 Alkanes

Many Elderly Problems (?) Build Pension Houses (methane, ethane, propane, butane, pentane, hexane

Isomer

Molecules that have the same molecular formula but different structural arrangement of atoms.

Displayed Formula

Illustrates the arrangement of atoms for each element in space and includes the bonds between atoms.

Molecular Formula

A formula that shows the actual number of atoms for each element in a compound.

Homologous Series

A family of hydrocarbons with similar chemical properties who share the same general formula.

Features of a Homologous Series

They have the same general formula and the same chemical properties.

Combustion

When a fuel (hydrocarbon) reacts with oxygen to produce carbon dioxide and water.

Products of Complete Combustion

Carbon dioxide and water.

Substitution Reaction

When an atom in a compound is replaced by another atom.

Halogenation Reaction of Methane

Methane + bromine -> Bromomethane + hydrogen bromide (CH4 + Br2 -> CH3Br + HBr).

Condition for Halogenation

Requires UV light.

Colour Change in Halogenation of Methane

The mixture turns from orange to colourless.

Cracking

The thermal decomposition of a long chain hydrocarbon into small chain molecules.

Catalyst and Temperature for Cracking

Alumina and around 600-700 °C.

Why Crack Long Chain Hydrocarbons

Small chain hydrocarbons are more useful and we have a surplus of long chain hydrocarbons from crude oil.

Thermal Decomposition

When heat is used to break down a compound.

Saturated Hydrocarbon

A hydrocarbon that only contains single carbon bonds.

General Formula for an Alkene

CnH2n.

Why Alkenes Are Unsaturated

They contain a double bond between two carbon atoms.

Test for Alkane or Alkene

Add bromine water: yellow stays for alkane, turns colourless for alkene.

Incomplete Combustion

Occurs when a fuel burns in insufficient oxygen, producing carbon monoxide.

Toxicity of Carbon Monoxide

It stops blood cells from transporting oxygen efficiently.

Polymer

A long chain molecule made from monomers joined end to end.

Monomer

A small molecule that can be joined to another monomer to make a polymer.