Organic Chemistry

Question 2

What is crude oil?

Answer 2

A finite resource found in rocks, made from ancient biomass (mainly plankton) buried in mud.

Question 3

What is a finite resource?

Answer 3

A resource that will eventually run out (e.g., crude oil).

Question 4

What is a mixture?

Answer 4

A combination of two or more substances that are not chemically combined and retain their own properties.

Question 5

Why can crude oil be separated by fractional distillation?

Answer 5

It is a mixture, so the components have different boiling points.

Question 6

What are hydrocarbons?

Answer 6

Molecules made of carbon and hydrogen atoms only.

Question 7

What is the general formula of alkanes?

Answer 7

CnH(2n+2)

Question 8

What are the first four alkanes?

Answer 8

Methane, Ethane, Propane, Butane (Monkeys Eat Peanut Butter).

Question 9

How does the length of a hydrocarbon chain affect its properties?

Answer 9

Shorter chains: Less viscous, Lower boiling point, More flammable. Longer chains: More viscous, Higher boiling point, Less flammable.

Question 10

What are petrochemicals?

Answer 10

Chemicals obtained from crude oil, used to make plastics, lubricants, detergents, and solvents.

Question 11

How does fractional distillation separate hydrocarbons?

Answer 11

Different hydrocarbons condense at different temperatures because of varying boiling points.

Question 12

Which fractions are produced in fractional distillation?

Answer 12

Top (low b.p., short-chain): LPG, petrol. Middle: Kerosene, diesel. Bottom (high b.p., long-chain): Heavy fuel oil, bitumen.

Question 13

What is complete combustion of hydrocarbons?

Answer 13

Hydrocarbon + Oxygen → Carbon dioxide + Water

Question 14

What is incomplete combustion?

Answer 14

Hydrocarbon burns in limited oxygen, producing carbon monoxide (CO) or carbon (soot).

Question 15

Why is carbon monoxide dangerous?

Answer 15

It binds to haemoglobin, preventing oxygen transport in blood.

Question 16

What is cracking, and why is it important?

Answer 16

Breaking down long hydrocarbons into shorter, more useful ones (alkanes + alkenes). Produces fuels and alkenes for making polymers.

Question 17

What are the two types of cracking?

Answer 17

Catalytic cracking: Vaporised hydrocarbons pass over a hot catalyst. Steam cracking: Hydrocarbons mixed with steam and heated to a high temperature.

Question 18

What is the test for alkenes?

Answer 18

Add bromine water: Orange → Colourless if an alkene is present.

Question 19

What is the general formula for alkenes?

Answer 19

C_nH_(2n)

Question 20

Why are alkenes unsaturated?

Answer 20

They contain a carbon-carbon double bond (C=C).

Question 21

What are functional groups?

Answer 21

Groups of atoms responsible for an organic molecule’s reactions (e.g., -OH for alcohols, -COOH for acids).

Question 22

How do alkenes differ from alkanes in reactivity?

Answer 22

Alkenes are more reactive because of the C=C double bond.

Question 23

How do alkenes react with oxygen?

Answer 23

Incomplete combustion, producing carbon monoxide, carbon, and water.

Question 24

What happens when alkenes react with hydrogen?

Answer 24

The C=C double bond breaks, forming an alkane (hydrogenation reaction).

Question 25

What conditions are needed for hydrogenation of alkenes?

Answer 25

Nickel catalyst, 150°C.

Question 26

What happens when alkenes react with water?

Answer 26

An alcohol is formed (hydration reaction).

Question 27

What conditions are needed for the hydration of alkenes?

Answer 27

Phosphoric acid catalyst, 300°C, 60-70 atm.

Question 28

What happens when alkenes react with halogens?

Answer 28

The double bond breaks, and the halogen atoms add across the C=C bond (e.g., ethene + bromine → dibromoethane).

Question 29

What is the functional group of alcohols?

Answer 29

-OH (hydroxyl group).

Question 30

What are the first four alcohols?

Answer 30

Methanol, Ethanol, Propanol, Butanol.

Question 31

How do alcohols react with sodium?

Answer 31

They produce a salt (e.g., sodium ethoxide) and hydrogen gas.

Question 32

How does ethanol react with oxidising agents?

Answer 32

Forms ethanoic acid (e.g., using acidified potassium dichromate).

Question 33

What happens when alcohols burn in air?

Answer 33

They combust to form carbon dioxide and water.

Question 34

How can ethanol be produced?

Answer 34

Fermentation: Glucose → Ethanol + Carbon dioxide. Conditions: Anaerobic, yeast, ~35°C.

Question 35

What is the functional group of carboxylic acids?

Answer 35

-COOH (carboxyl group).

Question 36

What are the first four carboxylic acids?

Answer 36

Methanoic acid, Ethanoic acid, Propanoic acid, Butanoic acid.

Question 37

What type of acid are carboxylic acids?

Answer 37

Weak acids; they only partially ionise in water.

Question 38

How do carboxylic acids react with metal carbonates?

Answer 38

They produce a salt, carbon dioxide, and water.

Question 39

How do carboxylic acids react with alcohols?

Answer 39

They form esters in the presence of an acid catalyst.

Question 40

What is an ester?

Answer 40

A compound with the functional group -COO-, formed from carboxylic acid + alcohol.

Question 41

What is the general word equation for esterification?

Answer 41

Carboxylic acid + Alcohol → Ester + Water ## Footnote E.g., Ethanoic acid + Ethanol → Ethyl ethanoate + Water

Question 42

What is polymerisation?

Answer 42

A reaction where small monomers join to form long-chain molecules (polymers).

Question 43

What is addition polymerisation?

Answer 43

A reaction where alkenes join together, with no other products formed.

Question 44

What is condensation polymerisation?

Answer 44

A reaction where monomers with two functional groups join, releasing small molecules (e.g., water).

Question 45

What are the four DNA bases?

Answer 45

Adenine (A), Thymine (T), Cytosine (C), Guanine (G).

Question 46

What are two other important naturally occurring polymers?

Answer 46

Starch (monomer = glucose), Cellulose (monomer = glucose).