Crude oils and fuels

How is crude oil (mixture) formed

↳ Plankton being buried in mud over a million years

Why is hydrocarbons used as fuels?

↳ When they react with oxygen they realised lots of energy

↳ This is called combustion

What is complete combustion

↳ Complete combustion is when the only products are carbon dioxide and wate

If a hydrocarbon has a short chain then what properties (flammability,bp,viscosity) does it have?

↳ Flammability-high

↳ Boiling point (bp) - low

↳ Viscosity - low (very runny)

↳ Therefore is more useful as fuels as it combusts easier

What are alkanes?

↳ A hydrocarbon with only a single covalent bond

What is the formula foe alkanes?

↳ C_nH_2n+2

↳ For evry carbon double it and add 2 to find out the amount of hydrogens

↳ Half and minus 2 for amount of carbons

What is fractional distillation?

↳ Seperating hydrocarbons in crude oil based on their boiling points

↳ All molecules in a fraction have a similar number of carbon atoms

What happens in fractional distillation?

↳ Crude oil is vapourised (turns into gas)

↳ 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

↳ This is done as shorter hydrocarbons are more useful as they are in higher demand

What does cracking produce

↳ Shorter alkanes and alkenes

What is catalytic cracking?

↳ Heat up the hydrocarbon to 550° and use a catalyst (pottery)

What is steam cracking?

↳ Heat to 850° without a catalyst

What are alkenes

↳ Hydrocrabons that contain at least 1 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