Hydrocarbons

How is crude oil formed?

↳ Plankton being buried in mud for over a million years

Why is hydrocarbons used as fuels?

↳ When they react with oxygen they realised lots of energy (combustion)

What is complete combustion?

↳ The only products are carbon dioxide and wate

What properties do short alkanes have (3)?

↳ Flammability-high

↳ Bp- low

↳ Viscosity - low (runny)

↳ Combusts easier = more useful

What are alkanes?

↳ A hydrocarbon with only a single covalent bond

What is the formula for alkanes?

↳ C_nH_2n+2

What is fractional distillation?

↳ Seperating hydrocarbons in crude oil based on their boiling points

What happens in fractional distillation (5)?

↳ Crude oil is vapourised

↳ The hydrocarbon gases enter the column

↳ The hydrocarbon gases rise up then cool down

↳ When the different hydrocarbons reach their bp in the column they condense

↳ The hydrocarbon fractions are colected

What is cracking?

↳ When you break up longer hydrocarbons into shorter ones

What is the difference between catalyctic and steam cracking?

↳ Catalyctic-heat up the hydrocarbon to 550° and use a catalyst (pottery)

↳ Steam-heat to 850° without a catalyst

What are alkenes?

↳ Hydrocrabons that contain at least one double bond (=) between their carbon atoms

What is the use of alkenes?

↳ To create fuels and other polymers

How do you test for alkanes/alkenes?

↳ Mix with bromine water

↳ Stays orange = alkane

↳ Turns colourless = alkene