Organic chemistry (up to esters)

Question 1

What is a hydrocarbon?

Answer 1

any compound formed from only hydrogen and carbon atoms

Question 2

What is a homologous series?

Answer 2

a group of organic compounds that react in a similar way

Question 3

What are saturated compounds?

Answer 3

compounds where each carbon atom forms four single covalent bonds

Question 4

What are alkanes?

Answer 4

the smallest type of hydrocarbon with single carbon bonds (C-C)
a homologous series (all react in a similar way)
saturated compounds

Question 5

What is the general formula for an alkane?

Answer 5

CnH2n+2

Question 6

What are the first four alkanes?

Answer 6

methane
ethane
propane
butane

Question 7

How do the properties of hydrocarbons change as the chain gets shorter?

Answer 7

the shorter the chain…

• the more runny and less viscous (gloopy) it is
• the more volatile it is (turns into a gas at a lower temp so has a lower boiling point)
• the more flammable the hydrocarbon is

Question 8

When does complete combustion occur?

Answer 8

when there is a plentiful supply of oxygen

Question 9

What are the waste product of the complete combustion of any hydrocarbon?

Answer 9

carbon dioxide and water vapour

Question 10

(complete combustion of a hydrocarbon)

hydrocarbon + oxygen ->

Answer 10

carbon dioxide + water (+ energy)

Question 11

What is crude oil?

Answer 11

a fossil fuel formed from remains of organisms buried in mud over millions of years, which can be drilled up to be used
it is also a mixture of lots of different hydrocarbons

Question 12

What is fractional distillation used for?

Answer 12

used to separate hydrocarbon fractions in crude oil

Question 13

Explain the process of fractional distillation.

Answer 13

• the oil is heated and the gas enters a fractioning column
• there’s a temperature gradient (hotter at the bottom and cooler towards the top)
• longer hydrocarbons have higher boiling points so condense into liquids lower down the column so drain off lower down the column
• shorter hydrocarbons have lower boiling points so condense towards the top of the column

Question 14

What is cracking?

Answer 14

splitting long chain hydrocarbons into smaller hydrocarbons

because shorter chain hydrocarbons are more useful

Question 15

What are the two types of cracking?

Answer 15

catalytic cracking (using a catalyst)
steam cracking (using steam)

Question 16

What happens in catalytic cracking?

Answer 16

• long chain hydrocarbons are heated to vaporise them
• the vapour is passed over a hot powdered aluminium oxide catalyst
• the long chain hydrocarbons split apart on the surface of the catalyst

Question 17

What happens in steam cracking?

Answer 17

• long chain hydrocarbons are heated to vaporise them
• the long chain hydrocarbons are mixed with steam
• then they are heated to a very high temperature

Question 18

What are alkenes?

Answer 18

unsaturated hydrocarbons with a double carbon bond (C=C)

they are much more reactive than alkenes

Question 19

What is the general formula for alkenes?

Answer 19

CnH2n

Question 20

What are the first four alkenes?

Answer 20

ethene
propene
butene
pentene

Question 21

(incomplete combustion of alkenes in air)

alkene + oxygen ->

Answer 21

carbon +carbon monoxide + carbon dioxide + water (+ energy)

Question 22

What is a functional group?

Answer 22

a group of atoms in a molecule that determine how the molecule typically reacts
eg. all alkenes have a C=C bond so all act in a similar way

Question 23

What is hydrogenation?

Answer 23

the addition of hydrogen
hydrogen can react with the double bonds of carbon (in an alkene) to open up the double bond and form the equivalent alkane

Question 24

Alkenes react via addition reactions, what does this mean?

Answer 24

the carbon-carbon double bond will open up to leave a single bond and a new atom is added to each carbon

Question 25

How do alkenes react with halogens?

Answer 25

in addition reactions | the molecules formed are saturated, with the C=C carbons each becoming bonded to a halogen atom

Question 26

How can you test for alkenes?

Answer 26

alkenes turn bromine water colourless (whereas if it is added to a saturated compound it would remain bright orange)

Question 27

What happens when steam reacts with alkenes?

Answer 27

water is added across the double bond and an alcohol is formed eg. ethene and water in the presence of a catalyst produce ethanol, which can be used to make alcohol in industry

Question 28

What are polymers?

Answer 28

long molecules formed when lots of small molecules (monomers) join together

Question 29

What is polymerisation?

Answer 29

the reaction where monomers join together to form polymers

Question 30

What is addition polymerisation?

Answer 30

when lots of unsaturated monomer molecules (alkenes) open up their double bonds and join together to form polymer chains (the only product is the polymer)

Question 31

What is the general formula of an alcohol?

Answer 31

CnH2n+1OH

Question 32

What are alcohols?

Answer 32

a homologous series formed from steam and alkenes which have an -OH functional group (they all end in -ol)

Question 33

What are the first four alcohols?

Answer 33

methanol ethanol propanol butanol

Question 34

What properties do the first four alcohols have?

Answer 34

- are flammable - undergo complete combustion in air (to produce carbon dioxide and water) - are all soluble in water (their solutions have a neutral pH) - react with sodium - can be oxidised by reacting with oxygen to form carboxylic acids

Question 35

What can alcohols be used for? (And why?)

Answer 35

used as/in... - solvents in industry (because they can dissolve things water can and can't dissolve) - fuels (because they are not smelly) - alcoholic drinks (ethanol can be made for this by fermentation)

Question 36

What is fermentation?

Answer 36

The reaction where (an enzyme in) yeast converts sugars into ethanol and carbon dioxide.

Question 37

What conditions are required for fermentation?

Answer 37

around 37°C in a slightly acidic solution under anaerobic conditions

Question 38

What are carboxylic acids?

Answer 38

a homologous series of compounds made when alcohols react with oxygen which have the functional group -COOH (they all end in -anoic acid)

Question 39

What are the first four carboxylic acids?

Answer 39

methanoic acid ethanoic acid propanoic acid butanoic acid

Question 40

How do carboxylic acids react?

Answer 40

- they react with carbonates to produce a salt, water and carbon dioxide (these salts start with the first part of the carboxylic acid's name and end in -anoate) - they dissolve in water and ionise to release H+ ions but they don't ionise completely so form weak acidic solutions

Question 41

What are esters?

Answer 41

a group formed from an alcohol and a carboxylic acid (in the presence of an acid catalyst) with the functional group -COO

Question 42

alcohol + carboxylic acid ->

Answer 42

ester + water

Question 43

What is condensation polymerisation?

Answer 43

where monomers which contain different functional groups react together so that bonds form between them to make a polymer chain for each bond formed, a small molecule (eg. water) is produced

Question 44

What are the differences between addition polymerisation and condensation polymerisation?

Answer 44

- addition uses only one monomer type (with the functional group C=C) but condensation uses two monomer types (each with two of a different functional group to eachother) or one monomer type (which has two different functional groups) - addition only forms a polymer but condensation forms a polymer and a small molecule

Question 45

Name some examples of naturally occurring polymers

Answer 45

- proteins - DNA - carbohydrates

Question 46

What is formed from the monomers amino acids?

Answer 46

proteins via condensation polymerisation

Question 47

What is formed from the monomers nucleotides?

Answer 47

DNA

Question 48

What is formed from the monomers simple sugars?

Answer 48

larger polymers like starch and cellulose