7a hydrocarbons and crude oil

What is a hydrocarbon

Any compound that’s formed from carbon and hydrogen only

What are alkanes

Saturated hydrocarbons

What are the first four alkanes in the homologous series

Methane, ethane, propane, butane

What is the chemical formula of alkanes

CnH2n+2

Properties of alkanes

Boiling point increases with chain length, shorter alkanes are more flammable and volatile, longer alkanes are more viscous

What is the main use for hydrocarbons

Fuels

What is complete combustion

When a hydrocarbon reacts with oxygen to form carbon dioxide and water releasing lots of energy in the process

What type of reaction is complete combustion

Exothermic

What order do you balance elements in a complete combustion equation

Carbons, hydrogens, oxygens

Properties depend on…

…length of hydrocarbons

What is crude oil

A mixture of different compounds mainly hydrocarbons.

How is crude oil formed

From remains of dead plants and animals mainly plankton that died millions of years ago and were buried in mud high pressure and temperatures underground

crude oil is a…

…finite resource

What is the process of Fractional distillation

1) crude oil heated so it evaporates and then entered in fractionating column

2) fractional column is hottest at bottom and coolest at the top

3)hot gas rises to column and gradually cools

4)different compounds in mixtures have different boiling points do condense at different temperatures and therefore different levels

What are petrochemicals

Substances from crude oil

What are petrochemicals used as

Feedstock

What are petrochemicals used to make

Solvents, lubricants, polymers, detergents

What is cracking

Process of breaking down longer hydrocarbons into smaller more useful hydrocarbons

What type of reaction is cracking

A thermal decomposition reaction

What is the process of steam cracking

Heat long chain hydrocarbon till its a gas, mix vapourised hydrocarbon with steam and then heat to very high temperature, causing long chain hydrocarbon to split into shorter ones

What is process of catalytic cracking

Heat long chain hydrocarbon till it’s a gas, pass hydrocarbon vapour over a hot powdered catalyst, as hydrocarbon contacts catalyst it splits into two smaller hydrocarbons

Cracking chemical reaction

Long chain HC —> small alkane + alkane

What can alkanes be used to produce

Polymers

What are alkenes

Unsaturated hydrocarbons

Alkenes are more ___ than alkanes

Reactive

What is test for alkenes

Bromine water, will decolourises when alkene solution is added