Organic chemistry

Question 1

How are coal, oil and natural gas formed?

Answer 1

Formed as a result of heat and pressure

Question 2

How is petroleum separated into smaller hydrocarbons?

Answer 2

Fractional distillation

Question 3

Order of hydrocarbons in fractionating column

Answer 3

Question 4

What is a fraction

Answer 4

A mixture of compounds with a similiar boiling point

Question 5

What is refinery gas used for

Answer 5

Bottled gas

Question 6

What is gasoline used for

Answer 6

Petrol

Question 7

What is kerosene used for

Answer 7

Jet fuel

Question 8

What is diesel used for

Answer 8

Train and car fuel

Question 9

What is fuel oil used for

Answer 9

Central heating

Question 10

What is bitumen used for

Answer 10

Road and roof tar

Question 11

What is a homologous series

Answer 11

A family of hydrocarbons which have similiar features and chemical properties due to being in the same functional group

Question 12

What test can be used to tell which is an alkane and which is an alkene

Answer 12

Bromine water -

Alkanes will be orange

Alkenes wil decolourise

Question 14

What do all members of a homologous series have

Answer 14

Same general formula

Same functional group

Similiar chemical properties

Gradiation in their physical properties

Difference in molecular formula between one member and the next is CH2

Question 15

What is a functional group

Answer 15

A group of atoms bonded in a specific arrangement which is responsible for the characteristic reactions of each member of a homologous series

Question 16

What is a structural isomer

Answer 16

Compounds with the same molecular formula but different structural formula

There are two different types of structural isomer which are chain and position

In chain the structure of the carbon chain differs

In position the position of the functional group differs

Question 17

example of chain isomer

Answer 17

Question 18

example of position isomer

Answer 18

Question 19

What are alkanes

Answer 19

Saturated hydrocarbons

Contain no double bonds

Colourless compounds which have a gradual change on their physical properties as the number of carbon atoms in the group increases

Generally unreactive compounds but they do ungo combustion reactions and can be cracked into smaller alkanes and react with halogens in the presence of light

Question 20

What is the main component of natural gas

Answer 20

Methane

Question 21

Combustion of methane

Answer 21

Question 22

What is a substitution reaction

When do substitution reactions occur on alkanes

Answer 22

Substitution reaction - where one atom of one element/compound is swapped with an atom from another compound

Alkanes unergo substitution reactions with halogens in the presence of light

Question 23

What are alkenes

Answer 23

Alkenes are hydrocarbons which contain a double bond

They are unsaturated compounds

Question 24

How are alkenes and hydrogen made?

Answer 24

The catalyctic cracking of long alkane chains

Question 25

What is catalyctic cracking?

Answer 25

The breakdown of less-useful longer hydrocarbon chains and shorter useful hydrocarbons

Question 26

How is catalytic cracking conducted

Answer 26

Fractions containing large hydrocarbon molecules are heated at 600-700 degrees to vaporize them Vapours are then passed over a catalyst of silica and alumina This breaks the covalent bonds causing thermal decomposition The longer hydrocarbon chain has been broken up into shorter chains of alkenes and alkanes

Question 27

Example of alkanes being cracked

Answer 27

Kerosene and diesel oil are often cracked to form petrol other alkenes and hydrogen

Question 28

How does bromine water show that one is an alkane and the other an alkene?

Answer 28

Bromine water is an orange coloured solution of bromine When bromine water is shaken with an alkane, it remains orange as there no C=C bonds present; so the bromine remains in solution When bromine water is shaken with an alkene, it decoloursies due to the presence of a C=C bond The bromine atoms add across the C=C hence the solution no longer contains orange bromine water

Question 29

What type of reaction occurs between an alkene and bromine water

Answer 29

An addition reaction

Question 30

Example of an addition reaction

Answer 30

Question 31

What is addition polymerisation

Answer 31

The joining of monomers to form addition polymers This only occurs in monomers containing C=C bonds

Question 32

What occurs in addition polymerisation

Answer 32

One of the bonds in each double bond breaks and forms a bond with the adjacent monomer An example of an synthesized alkene monomer in poly-ethene

Question 33

What is a hydrogenation reaction

Answer 33

When an alkene is reacted with H2 to form an alkane This reaction occurs at 150\*C using a nickel catalyst

Question 34

Practical use of hydrogenation reaction

Answer 34

Turning vegetable oils into margerine for supermarkets

Question 35

What are the conditions and products of alkene + steam

Answer 35

Conditions - 300\*C, 60-70atm, concentrated phosporic acid catalyst Alkene + water --\> alchahol This is called the hydration of alkene

Question 36

What is an alchahol

Answer 36

Contains the -OH functional group

Question 37

What is ethanol

Answer 37

An alchahol - C2H5OH Found in alchaholic drinks, used in cars as a solvent for fuel Ethanol burns in excess to form carbon dioxide and water

Question 38

What are the two methods for the manufacture of ethanol

Answer 38

Hydration of ethene fermentation of glucose

Question 39

How is the fermentation of glucose carried out (ethanol manufacture)

Answer 39

Sugar or starch is added in water and yeast is added Mixture ferments for a few days with no oxygen between the tempuratures 15 and 35\*C Yeast contains enzymes that break down the starch or sugar to glucose If the tempurature is too slow the reaction rate will be too low If the tempurature is too high the enzymes denature The yeast respires anaerobically to form CO2 and ethanol The yeast are killed off oncethe level of alchahol is 15%

Question 40

Balanced equation of fermentation of glucose

Answer 40

Question 41

Comparison of fermentation to hydration of ethene - hydration of ethene

Answer 41

Hydration of ethene - complex set up uses non-renewable resources fast rate of reaction produces pure ethanol No greenhouse gases produced Reaction conditions - high temp and pressure

Question 42

Comparison of fermentation and hydration of ethene - fermentation

Answer 42

Simple equipment needed Uses re-newable resources Batch proccess - inefficient Very slow process Produces a dilute solution of alchahol which requires further processing

Question 43

What is a carboxylic acid

Answer 43

The homologous series containing the functional group -COOH Colourless liquid Weak acids, typical acidic properties They react with alkaline solutions, turn blue litmus red, and form salts called ethanoates

Question 44

Properties of ethanoic acid

Answer 44

Weak acid Dissociates slightly in water Equilibrium lies far to the left in ionization ethanoic acid reacts with more reactive metals, carbonates and hydroxides

Question 45

How to make carboxylic acids - oxidation by fermentation

Answer 45

The microbial fermentation of alchahol will produce a weak solution of vinegar This occurs when a bottle of wine is opened as the bacteria in the air use the oxygen in the air to oxidise the ethanol in the wine The acidic, vinegary taste of opened wine is due to the production of ethanoic acid

Question 46

Production of carboxylic acids - alchahols heated with potassium manganate

Answer 46

Alchahols are heated with potassium mangante in a vessel with a condenser attached to the top The condenser prevents the volatile alchahol from escaping from the reaction vessel as alchahols have low boiling points

Question 47

How are esters made

Answer 47

By adding alchahols and carboxylic acids togeth

Question 48

What are esters

Answer 48

Esters are compounds with the functional group R-COO-R Esters are sweet smelling oily liquids in food flavourings and perfumes