C7 - Organic Chemistry

Question 1

Define a hydrocarbon

Answer 1

a compound containing carbon and hydrogen only

Question 2

What happens as you increase the chain length of a hydrocarbon?

Answer 2

• becomes more viscous
• higher boiling points
• less flammable
• dark in colour
• less volatile
• less useful

Question 3

Describe how fractional distillation works

Answer 3

• oil is heated and evaporated until most of it is a gas
• the gas rises through a fractionating column
• the long hydrocarbons have high boiling points so they condense back to liquids near the bottom
• the shorter hydrocarbons have lower boiling points so they condense higher in the column where it’s cooler
• crude oil mixture will be separated into different fractions

Question 4

Define a saturated hydrocarbon

Answer 4

single carbon bonds only
(C-C)

Question 5

Define alkanes

Answer 5

they are a group of saturated hydrocarbons - the simplest type of hydrocarbon

Question 6

What is the general formula of an alkane?

Answer 6

C(n) H (2n+2)

Question 7

Name the first 4 alkanes

Answer 7

1) methane
2) ethane
3) propane
4) butane

Question 8

What happens to the flammability as the length of the hydrocarbon chain increases?

Answer 8

the flammability decreases because smaller molecules evaporate easily and the vapour burns

Question 9

What happens to the volatility as the length of the hydrocarbon chain increases?

Answer 9

the volatility decreases because the intermolecular forces are stronger so it requires more energy to break which means they have higher boiling points making them less volatile

Question 10

What happens to the viscosity (thickness) as the length of the hydrocarbon chain increases?

Answer 10

the viscosity increases because the intermolecular forces are stronger and longer chain hydrocarbons get more tangled which means more viscous

Question 11

Define an alkene

Answer 11

a hydrocarbon that has 1 double covalent bond (C=C) between two carbon atoms - they are unsaturated

Question 12

What is the general formula for alkenes?

Answer 12

C (n) H (2n)

Question 13

Name the first 4 alkenes

Answer 13

1) ethene
2) propene
3) butene
4) pentene

Question 14

How do you test if a substance is an alkane or an alkene?

Answer 14

add bromine water
- if it remains orange = alkane
- if it becomes colourless = alkene

Question 15

Define cracking

Answer 15

breaking down a long hydrocarbon chain into an alkane and alkene

Question 16

Describe the process of cracking

Answer 16

• vaporise them
• mix them with steam
• heat them to a very high temperature
  (called steam cracking)

Question 17

What are the 2 things you need for cracking?

Answer 17

• heat (to vaporise the hydrocarbons)
• catalyst (to increase the rate of the reaction)

Question 18

What is the word equation for the complete combustion of hydrocarbons?

Answer 18

hydrocarbon + oxygen –> carbon dioxide + water

Question 19

What is the word equation for the incomplete combustion of hydrocarbons?

Answer 19

hydrocarbon + oxygen –> carbon monoxide + water

Question 20

When would complete/incomplete combustion occur?

Answer 20

complete - in a high oxygen supply
incomplete - in a low oxygen supply

Question 21

Define a monomer

Answer 21

a small molecule that can be joined together to form a polymer

Question 22

Define a polymer

Answer 22

long chain molecule made up of lots of monomer molecules

Question 23

Define an addition reaction

Answer 23

when a double carbon bond (C=C) breaks and new atoms add to each carbon atom

Question 24

Define polymerisation

Answer 24

a reaction where lots of small monomer molecules join together in a long chain

Question 25

Name the 4 reactions alkenes can do

Answer 25

- hydrogenation - hydration - halogenation - combustion (incomplete)

Question 26

Describe hydrogenation

Answer 26

alkenes react with hydrogen ( + catalyst) to make an alkane requires very high temperature

Question 27

Describe hydration

Answer 27

alkene reacts with steam (+ catalyst) to form alcohol

Question 28

Describe halogenation

Answer 28

alkenes react with the halogens to form a dihalide alkane

Question 29

Describe combustion of alkenes

Answer 29

alkenes react with the oxygen in the air and form carbon monoxide and water it's incomplete which results in a smoky yellow flame and less energy being released

Question 30

Define alcohols

Answer 30

organic compounds that contain the OH functional group

Question 31

What is the general formula for alcohol?

Answer 31

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

Question 32

Name the first 4 alcohols

Answer 32

- methanol - ethanol - propanol - butanol

Question 33

Describe the solubility and pH of alcohol

Answer 33

- alcohols are soluble - they have a neutral pH

Question 34

Describe what happens when alcohols react with sodium

Answer 34

- sodium sinks - more dense than ethanol - hydrogen is produced - mixture goes alkali

Question 35

Describe the 2 ways to make alcoholic drinks

Answer 35

- fermentation uses an enzyme in yeast to convert sugars into ethanol and carbon dioxide - reacting ethene with water vapour in the presence of a catalyst (hydration)

Question 36

What are some pros and cons of fermentation to produce ethanol?

Answer 36

+ renewable + requires less energy + cheaper - don't get pure ethanol - slower

Question 37

What are some pros and cons of hydration to produce ethanol?

Answer 37

+ no waste products + faster - non-renewable - requires more energy - more expensive

Question 38

What is the functional group for carboxylic acids?

Answer 38

COOH

Question 39

What is the general formula for carboxylic acids?

Answer 39

C (n) H (2n-1) COOH

Question 40

Name the first 4 carboxylic acids

Answer 40

- methanoic acid - ethanoic acid - propanoic acid - butanoic acid

Question 41

Carboxylic acids are ...... acids so they .................. in solutions.

Answer 41

- weak - partially ionise

Question 42

Carboxylic acids form salts that end in .........

Answer 42

-anoate

Question 43

What is the equation to make esters?

Answer 43

carboxylic acid + alcohol (+catalyst) --> ester + water

Question 44

What is the functional group for esters

Answer 44

COO

Question 45

What are the purpose of esters?

Answer 45

- they are volatile - have unique fragrances / tastes

Question 46

Define a diol

Answer 46

a monomer with 2 hydroxyl (functional) groups

Question 47

Explain how a polyester is formed through condensation polymerisation

Answer 47

- react a dicarboxylic acid with a diol - use lots of each - water is produced as a byproduct - polyester will be a product

Question 48

How many types of monomers are needed for condensation polymerisation?

Answer 48

- two monomer types, each containing two of the same functional group OR - one monomer type with two different functional groups

Question 49

Give 3 examples of naturally occurring polymers

Answer 49

- proteins - starch / cellulose - DNA

Question 50

What are polypeptides?

Answer 50

- amino acids form polymers known as polypeptides - polypeptides form proteins

Question 51

What are the bonds between amino acids (formed in a condensation reaction) called? (3 names)

Answer 51

- amide link - peptide bond - amide bond

Question 52

What type of reaction takes place when amino acids combine to form a polypeptide?

Answer 52

condensation reaction

Question 53

Which functional groups does an amino acid have? (3)

Answer 53

- a carboxylic acid group - an amino group - an 'R' group

Question 54

Which monomers combine to form DNA?

Answer 54

nucleotides

Question 55

What are the three elements that make up carbohydrates?

Answer 55

- carbon - oxygen - hydrogen

Question 56

What is a feedstock?

Answer 56

a raw material used to provide reactants for an industrial reaction

Question 57

What is a petrochemical?

Answer 57

a substance made from crude oil via chemical reactions