Organic chemistry - IGCSE

Question 1

General formula

Answer 1

A chemical formula which applies to a class of compounds, representing the composition of the atoms present in the compound

Question 2

Homologous series

Answer 2

A series of compounds with the same functional group and similar chemical properties

Question 3

Functional group

Answer 3

The group of atoms responsible for how a particular compound reacts
All compounds in the same homologous series have the same functional group

Question 4

Repeat unit

Answer 4

The part of a polymer whose repetition would produce the complete polymer chain

Question 5

Alkanes

Answer 5

The most common hydrocarbon found in crude oil
Alkanes have the general formula CnH2n+2

Question 6

Alkenes

Answer 6

Hydrocarbons with a double bond between two of the carbon atoms in their chains, causing them to be unsaturated
They have the general formula CnH2n

Question 7

Carboxylic acids

Answer 7

Organic compounds with the functional group -COOH

Question 8

Ester

Answer 8

The product of a condensation reaction between a carboxylic acid and alcohol
They contain the functional group -COO- and are volatile compounds with distinct smell

Question 9

Monomer

Answer 9

Small short chain molecules which can join together to form a long chain polyester

Question 10

Hydrocarbons

Answer 10

Molecules that are made up of hydrogen and carbon atoms only

Question 11

Saturated hydrocarbons

Answer 11

A hydrocarbon compound containing only single bonds between carbon atoms
Alkanes are saturated compounds

Question 12

Unsaturated hydrocarbons

Answer 12

A compound that contains double or triple carbon bonds so that it doesn’t contain the maximum number of hydrogen atoms
Alkenes are unsaturated compounds

Question 13

Polymer

Answer 13

Large long-chain molecules made up of lots of small monomers joined together by covalent bonds

Question 14

Addition polymerisation

Answer 14

The reaction in which many small molecule monomers bond together to form a long chain polymer

Question 15

Condensation polymerisation

Answer 15

Reactions in which monomers join together and lose small molecules, such as water
These reactions involve monomers with two functional groups

Question 16

Cracking

Answer 16

A process that involves breaking down larger hydrocarbons to produce smaller more useful molecules
Cracking can be done by catalytic cracking or steam cracking

Question 17

Catalytic cracking

Answer 17

Long-chain hydrocarbons are heated at 600-700C to turn them into a gas
The vapour is then passed over a silica or alumina catalyst
The long chain molecules split apart on the surface of the catalyst

Question 18

Steam cracking

Answer 18

Long-chain hydrocarbons are heated to turn them into a gas
The hydrocarbon vapour is then mixed with steam and heated to a very high temp which caused them to split into smaller molecules

Question 19

Combustion

Answer 19

The burning of a substance
Combustion of hydrogen fuels releases energy
During combustion, the carbon and hydrogen in the fuels are oxidised

Question 20

Complete combustion

Answer 20

Combustion carried out in sufficient oxygen
Water and carbon dioxide are the only products of the complete combustion of a hydrocarbon

Question 21

Incomplete combustion

Answer 21

Combustion which is carried out with insufficient oxygen
It can lead to the production of toxic carbon monoxide and carbon particulates

Question 22

Addition reaction

Answer 22

A reaction in which at least two molecules combine together to form a larger molecule

Question 23

Substitution reaction

Answer 23

A reaction in which a functional group of a compound is replaced by another functional group