alkanes

Question 1

saturated hydrocarbon

Answer 1

Saturated hydrocarbons contain only C-C single bonds.

Question 2

unsaturated hydrocarbon

Answer 2

Unsaturated hydrocarbons contain at least one C=C double bond.

Question 3

hydrocarbon

Answer 3

A hydrocarbon is a compound made up of hydrogen and carbon only.

Question 4

crude oil

Answer 4

Crude oil is a mixture of hydrocarbons.

Question 5

Fractional distillation

Answer 5

Fractional distillation is used to separate crude oil into fractions by boiling point.

Question 6

fractions

Answer 6

Crude oil fractions (sometimes called ‘petroleum fractions’) are mixtures of similar chain length hydrocarbons.

Question 7

catalytic cracking

Answer 7

Catalytic cracking can be used to break long hydrocarbons into shorter chain hydrocarbons and small alkenes, such as ethene. It requires heat and a zeolite catalyst.

Question 8

reforming hydrocarbons

Answer 8

Reforming hydrocarbons involves converting straight-chain alkanes into branched and cyclic alkanes.

Question 9

incomplete combustion

Answer 9

Incomplete combustion occurs with limited oxygen supply. If hydrocarbons are burnt incompletely, they will produce water and either carbon monoxide or carbon (soot), depending on how limited the oxygen is.

Question 10

biofuels

Answer 10

Biofuels are fuels made from some plant component: vegetable oils (for biodiesel) or fermented plant matter (for bioalcohols).

Question 11

carbon neutral

Answer 11

“Carbon neutral” can be used to describe a process where the amount of CO2 taken in making a fuel is the same as the amount of CO2 released when burning it.

Question 12

free radical

Answer 12

A free radical is a species with an unpaired electron.

Question 13

homolytic fission

Answer 13

Homolytic fission is where a bond breaks and one electron goes to each atom that was participating in the bond: it forms free radicals.

Question 14

heterolytic fission

Answer 14

Heterolytic fission is where a bond breaks and both electrons in the bond go to one atom that was participating in the bond: it forms ions, one will be + and one -.

Question 15

substitution

Answer 15

Substitution is a process/reaction type where one group or atom on a molecule is replaced by another.

Question 16

initiation

Answer 16

Initiation involves formation of free radicals as a product of homolytic fission

Question 17

propagation

Answer 17

Propagation involves free radical species reacting with non-free-radical species, forming more free radicals as well as new molecules.

Question 18

termination

Answer 18

Termination involves two free radicals meeting and forming a bond (so they are no longer reactive)