hydrocarbons

What is crude oil?

• Straight and branched chain alkanes

• Less amount of cycloalkanes and arenes

What is the uses of the petroleum gases fraction?

• fuels

• Feed stocks in some petrochemical processes

What is the uses of gasoline fraction in a fractional distillation?

• petrol

• Petrochemicals

What is the uses of naptha fraction in a fractional distillation?

Feedstock for petrochemical manufactures

What is the uses of kerosene fraction in a fractional distillation?

• production of aviation fuel

• Some Chemical processes

What is the uses of gas oil fraction in a fractional distillation?

• diesel fuels

• Heating

• Lubricating oils

What is the uses of residue in a fractional distillation?

• bitumen

• Waxes

• Less volatile lubricating oils

What is cracking?

Process that splits long chains of alkenes into a shorter chain alkanes and alkenes and hydrogen

What are the uses of cracking?

• increases amount of gasoline

• Increases branching in chains - factor for petrol

• Produces alkenes - important feedstock for chemicals

How does combustion in alkanes occur?

• chemicals react with oxygen to give out heat

• Makes CO2 and H2O

Is there is an incomplete combustion then what happens?

• lack of oxygen

• Creates CO and 2H2O

How are alkanes chlorinated?

• presence of UV light

• UV light needed to break bonds inn chlorine molecule

How is the chlorine bonds broken?

• chlorination - homolytic fission making chlorine free radical

How is free radicals reaction with alkanes?

• reactive

• In a free radical substitution reaction

draw a free radical mechanism.

• during initiation - need homolytic fission + UV light for it to work

• Can contain ethane - when 2 free radicals collide

Explain the bonding in ethene.

• overlap of s orbital creates a sigma bond

• Sideway overlap creates pi bond - joined together on top

• Pi bond in a region of high electron density

Draw an electrophilic addition with bromine and hydrogen

positive test for alkenes?

• Bronine water

• Brown —> colourless

Another way to test for alkenes?

• potassium manganates (vii)

• under cold

• Acid - dilute sulphuric acid - purple —> colourless

• Alkaline - sodium carbonate - purple —> dark green

What is carbocations stability and why?

• increases as the number of r groups increase ( h groups decrease)

• R groups contains greater electron density than h atoms - density attracted towards - reduces positive charge of carbon atoms

What is hydrogenation?

• hydrogen added to carbon double bond using nickel catylyst

• (Used in hydrogenated fats)

What is polymerisation?

Addition reactions to create a long chain polymer