Organic Chemistry

Question 1

What is crude oil?

Answer 1

A mixture of hydrocarbons

Question 2

What is a hydrocarbon?

Answer 2

A compound consisting of only hydrogen and carbon

Question 3

What is the general formula for alkanes?

Answer 3

H(n)C(2n+2)

Question 4

What are the first four hydrocarbon prefixes?

Answer 4

Meth-, Eth-, Prop-, But-

Question 5

What is cracking?

Answer 5

Breaking down long chain hydrocarbons into more useful short chain hydrocarbons using high temperature and pressure

Question 6

Describe catalytic cracking

Answer 6

• High temperature and pressure
• Vapours passed over hot catalyst
• Covalent bonds break + reform
• Products alkenes and alkanes

Question 7

What is the general formula of alkenes?

Answer 7

H(n)C(2n)

Question 8

What are the products of cracking used for?

Answer 8

Fuels

Question 9

How do you test for alkenes?

Answer 9

Mix with bromine water - positive result is colour change from orange to colourless

Question 10

Explain fractional distillation.

Answer 10

• Crude oil is heated to form a vapour
• This enters the bottom of the fractionating column
• The column is hotter at the bottom and cooler at the top
• Long chain hydrocarbons condense at the bottom
• Short chains condense at the top
• Some hydrocarbons remain as gases and leave through the top

Question 11

Name the products of complete combustion

Answer 11

Carbon dioxide and water

Question 12

Name the products of incomplete combustion

Answer 12

Carbon monoxide and water

Question 13

Why are alkene molecules unsaturated?

Answer 13

Because they contain two less hydrogen atoms than their corresponding alkane

Question 14

Name 3 of the properties of short chain hydrocarbons (+ why?)

Answer 14

• Low boiling points
• High flammability
• High volatility
• Low viscosity
• Because there are less intermolecular forces between molecules, meaning less energy is required to overcome them

Question 15

Name 3 of the properties of long chain hydrocarbons (+why)

Answer 15

• High boiling points
• Low flammability
• Low volatility
• High viscosity
• Because there are more intermolecular forces between molecules, meaning more energy is required to overcome them

Question 16

Name 3 products of crude oil

Answer 16

Petrol, solvents, lubricants, polymers, detergents, etc.

Question 17

What happens to the hydrogen and carbon atoms during combustion?

Answer 17

They are oxidised

Question 18

What is a functional group?

Answer 18

The part of an organic compound responsible for their chemical reactions (E.g. alkanes = C-C )

Question 19

What is the functional group of alkanes?

Answer 19

C-C

Question 20

What is the functional group of alkenes?

Answer 20

C=C

Question 21

What is the functional group of alcohols?

Answer 21

-OH

Question 22

What is the functional group of carboxylic acids?

Answer 22

-COOH

Question 23

What is the functional group of esters?

Answer 23

-COO-

Question 24

Write a word equation for the complete combustion of ethene

Answer 24

Ethene + Oxygen —> Carbon dioxide + Water

Question 25

Write a word equation for the incomplete combustion of ethene

Answer 25

Ethene + Oxygen ---> Carbon monoxide + Water

Question 26

What is a homologous series?

Answer 26

A group of organic compounds with the same function group (E.g. Alkanes)

Question 27

How do alkenes burn? (+why)

Answer 27

With a smoky flame, because of incomplete combustion

Question 28

Why are alkanes used for fuels and not alkenes?

Answer 28

Alkanes produce more energy per mole

Question 29

What are the products of alkenes reacting with water by addition reactions?

Answer 29

Alcohols (Prefix + -anol)

Question 30

Write a word equation for the addition reaction of ethene with water

Answer 30

Ethene + Steam (Water) ⇌ Ethanol

Question 31

Which addition reaction does NOT require a catalyst?

Answer 31

Reactions with halogens

Question 32

Describe steam cracking

Answer 32

- High temperature and pressure - Vapours mixed with steam - Products are alkenes and alkanes

Question 33

Which type of cracking requires the highest temperature?

Answer 33

Steam cracking

Question 34

What catalyst is used in addition reactions with hydrogen?

Answer 34

Nickel

Question 35

Are carboxylic acids strong or weak?

Answer 35

Weak - they partially ionise in water

Question 36

Do alcohols dissolve in water?

Answer 36

Yes

Question 36

What is the general formula for alcohols?

Answer 36

C(N) H(2n+1) OH

Question 37

What organic compound forms when alcohols are oxidised?

Answer 37

Carboxylic acids

Question 38

Give 2 uses of alcohols

Answer 38

- Fuels - Solvents

Question 39

Write a word equation for the reaction between ethanol and ethanoic acid

Answer 39

Ethanol + Ethanoic acid ⇌ Ethyl ethanoate + Water

Question 40

Name 3 naturally occurring polymers

Answer 40

- DNA - Protein - Starch - Cellulose

Question 41

What type of catalyst is used to make esters?

Answer 41

Sulfuric acid catalysts

Question 42

Name 2 qualities of esters

Answer 42

- Volatile - Smell sweet

Question 43

What are esters commonly used for?

Answer 43

Perfumes and flavourings

Question 44

How are polymers made?

Answer 44

- Addition polymerisation - Condensation polymerisation

Question 45

Write a word equation for the addition polymerisation of butene

Answer 45

Butene --> Poly(butene)

Question 46

What is the difference in the products of addition / condensation polymerisation?

Answer 46

Addition - produces a polymer Condensation - produces a polymer and a small molecule (H20)

Question 47

What happens in addition polymerisation?

Answer 47

The double bond in the monomer breaks and a longer polymer is formed

Question 48

What are diols? (+ example)

Answer 48

Molecules with 2 alcohol groups E.g. ethanediol (HO-CH2-CH2-OH)

Question 49

What is a dicarboxylic acid?

Answer 49

A carboxylic acid containing 2 -COOH groups

Question 50

What is the general equation for producing polyesters?

Answer 50

Diol + Carboxylic acid --> Polyester + Water

Question 51

Describe the structure of DNA

Answer 51

- Double helix - 2 polymer chains - Held in place by intermolecular forces - 4 nucleotides (monomers) that make up the polymer chains

Question 52

What are the 4 bases that make up nucleotides?

Answer 52

- Adenine - Thymine - Guanine - Cytosine