Organic Chemistry

Question 1

Crude oil

Answer 1

The remains of an ancient biomass, usually found in rocks

Question 2

Hydrocarbons

Answer 2

A chain of hydrogen and carbon atoms only

Question 3

Homologous series

Answer 3

A ‘family’ of organic compounds that have the same functional group and similar chemical properties

Question 4

Alkanes

Answer 4

Saturated hydrocarbons

C₍ₙ₎H₍₂ₙ₊₂₎

Question 5

Bonding in alkanes

Answer 5

Held together by covalent bonds

Single carbon bond

Question 6

Alkenes

Answer 6

Unsaturated hydrocarbons

C₍ₙ₎H₍₂ₙ₎

Question 7

Test for alkenes

Answer 7

Add orange bromine water to a liquid

If it changes colour from orange to colourless an alkene is present

Question 8

Bonding in alkenes

Answer 8

Held together by covalent bonds

Double carbon bond

Question 9

Properties in small hydrocarbons

Answer 9

Low boiling points

Lower viscosity (they flow more easily)

Higher flammability

Question 10

Properties in large hydrocarbons

Answer 10

High boiling points

Higher viscosity (they flow less easily)

Lower flammability

Question 11

Fractional distillation

Answer 11

Crude oil is vaporised and enters the fractioning column

The column is very hot at the bottom but much cooler at the top

As the vaporized oil rises, it cools and condenses.

Heavy fractions have a high boiling point and condense near
the bottom of the column

Lighter fractions have a lower boiling point and condense further up the column

Question 12

Complete combustion

Answer 12

When a hydrocarbon burns with a plentiful supply of O₂

Products are CO₂ and H₂O

Question 13

Incomplete combustion

Answer 13

When a hydrocarbon is burned with a bad supply of O₂

Products are CO, C, and H₂O

Question 14

Catalytic cracking

Answer 14

When an alkane is passed over a hot catalyst to break into a shorter alkane and an alkene

High temperature and pressure are needed

Question 15

Thermal cracking

Answer 15

When high temperatures and pressure are used to break down alkanes into a shorter alkane and alkene

Question 16

Alcohols

Answer 16

Functional group = OH

C₍ₙ₎H₍₂ₙ₊₁₎OH

Methanol, ethanol, propanol, butanol

Question 17

Making ethanol by fermentation

Question 18

Reaction of alcohol with sodium

Answer 18

When sodium is dropped into ethanol, sodium ethoxide and hydrogen are produced

Reactions are similar with methanol, propanol and butanol

Question 19

Reaction of alcohol burning in air

Answer 19

They either undergo complete or incomplete combustion dependent on the amount of O₂ available

Question 20

Reaction of alcohol with water

Answer 20

When methanol, ethanol and propanol are added to water, they easily mix to produce a solution

However, the solubility decreases as the length of the alcohol molecule increases, so butanol is less soluble than propanol

Question 21

Reaction of alcohol with an oxidising agent

Answer 21

Alcohols can be oxidised to produce carboxylic acids and water

Ethanol + oxidising agent → ethanoic acid + water

Question 22

Carboxylic acids

Answer 22

Functional group = COOH

C₍ₙ₎H₍₂ₙ₊₁₎COOH

Question 23

Reactions of carboxylic acids with metal carbonates

Answer 23

When they react with metal carbonates they produce a salt (ending in -anoate), water and carbon dioxide

Propanoic acid + magnesium carbonate ⟶ magnesium propanoate + water + carbon dioxide

Question 24

Reactions of carboxylic acids when dissolving in water

Answer 24

They produce acidic solutions, ionising and releasing H+ ions, but not completely so they form weak acid solutions

Question 25

Reactions of carboxylic acids with alcohols

Answer 25

They react in the presence of a catalyst to form an ester and water The catalyst can be concentrated sulphuric acid

Question 26

Esters

Answer 26

Functional group = COO Ends in -oate E.g. ethyl ethanoate

Question 27

Polymers

Answer 27

A substance made up of small repeating units Non-biodegradable and hard to recycle

Question 28

DNA

Answer 28

A polymer with a double helix (two polymer chains twisted) Made up of 4 different monomers (nucleotides)

Question 29

Other natural polymers

Answer 29

Starch, cellulose

Question 30

Polymerisation

Answer 30

Monomers join together to form very large molecules called polymers

Question 31

Addition polymerisation

Answer 31

Only forms one product E.g. poly(ethene)

Question 32

Condensation polymerisation

Answer 32

Involves monomers with two functional groups When the monomers react, a small by-product water is produced Ethanedioic acid + ethane diol ⟶ poly(ethylene) + water

Question 33

Amino acids

Answer 33

Amino acids have two different functional groups in a molecule Amino acids react by condensation polymerisation to produce polypeptides