C9

Hydrocarbons and crude oil

Crude oil

Finite resource formed from animal/plant remains over millions of years.

Fractional distillation separates by what property

boiling point

Fractional distillation of crude oil

Alkanes general formula

CnH2n+2

Saturated molecules

only contain single bonds

Displayed formula of propane

As alkanes increase in length… (4)

• the higher the boiling point

• the higher the viscosity (thicker)

• the lower the flammability

• the lower the volatility

Volatility

The ability to turn into a gas

Homologous series

A series of organic compounds with the same functional group:

• trends in physical

• same chemical properties

• same general formula

Name 3 fractions

• petrol (cars)

• kerosene (jet fuel)

• diesel (lorries)

How come the alkanes have different boiling points?

B.p increases as chain length increases due to stronger i.m.f. between the molecules.

Complete combustion

hydrocarbon + oxygen --> carbon dioxide + water

Incomplete combustion

hydrocarbon + oxygen → carbon monoxide + carbon + water

Cracking

The breaking down of long-chained alkanes to form a mixture of shorter-chained alkanes and alkenes.

Conditions for large scale cracking (2)

• 600-700 degrees

• Hot alumina catalyst

Small scale cracking diagram

Cracking of decane

Alkenes general formula

CnH2n

Alkene bromine water test

Turns orange to colourless

Alkenes are

unsaturated hydrocarbons

displayed formula of propene