Chemistry yr 11

What is crude oil?

A mixture of very large compounds made from the remains of ancient biomass, mainly plankton that was buried in mud millions of years ago

What is crude oil made up of?

It is mainly made up of molecules of hydrogen and carbon atoms only. These are hydrocarbons.

How can you separate unchanged hydrocarbons from crude oil?

By fractional distillation

How does fractional distillation work?

The mixture is heated until it evaporates and is placed in a tube which is hot at the bottom and cool at the top. The substances with high boiling points condense at the bottom and the ones with low boiling points condense at the top. This separates the different substances in a mixture as they have different boiling points

What is an alkane?

A saturated hydrocarbon which is a part of the homologous series (meaning they vary by CH2 and have similar chemical properties) and have no double bonds

What is the general formula for alkanes?

CnH2n + 2

What are the first 4 Alkanes

1. Methane

2. Ethane

3. Propane

4. Butane

What is combustion of hydrocarbons?

Burning of hydrocarbons which creates co2 and water which and green house gases and lead to climate change

What is incomplete combustion?

When not enough oxygen is present when burning so carbon dioxide, carbon monoxide, water and carbon particles are produced. These lead to carbon monoxide poisoning, global warming and global dimming

What is global dimming?

When carbon particles block the uv rays from the earth which can affect crops and wildlife

Volatility

how easily a substance turns into a gas

Viscosity

Thickness of a substance

Flammability

How easily a substance ignites

Boiling point

The temperature at which a substance boils and turns into a gas

Properties of short chained hydrocarbons

boiling point - low

volatility- high

viscosity - low

flamability - high

Long chained hydrocarbon properties

boiling point - high

volatility- low

viscosity- high

flammability- los

What is cracking

Making short chained hydrocarbons from less useful long chained hydrocarbons which are split into smaller more useful molecules

What is catalytic cracking?

When large hydrocarbons are broken into smaller molecules using heat and a catalyst. the smaller molecules are then separated by distillation i. molecules us