Organic Chemistry

Question 1

What is crude oil

Answer 1

A fossil fuel that is found underground in rocks

Question 2

How did crude oil form

Answer 2

1. Around 400-300 million years ago Plankton (sea creatures that cannot swim against a current, including algae, bacteria, protists and some animals) died and fell onto the sea floor.
   2: the dead plankton were then covered in mud over time
   3: Over millions of years, more and more sediment built up. The high temperature and pressure turned the dead plankton into oil and gas
   4: Now we use oil rigs to drill down through rock to reach the oil and bring it up to the surface

Question 3

What is biomass

Answer 3

A resource made from living or recently living organisms

Question 4

What is crude oil a form of

Answer 4

Ancient biomass

Question 5

Why is crude oil a finite resource

Answer 5

Because we cannot replace it as we use it up

Question 6

What are hydrocarbons

Answer 6

Compounds that contain hydrogen and carbon only

Question 7

What are most of the hydrogens in crude oil

Answer 7

Alkanes

Question 8

What are alkanes

Answer 8

A homologous series of saturated hydrocarbons with the general formule CnH2n+2(only C and H is big here )

Question 9

What does saturated mean in context of organic chemistry

Answer 9

A molecule that only contains single covalent bonds. It contains no double covalent bonds.

Question 10

Formula for alkanes

Answer 10

CnH2n

Question 11

What are the first seven alkanes called

Answer 11

Methane
Ethane
Propane
Butane
Pentane
Hexane
Heptane

Question 12

What do the two different parts of the names of organic compounds show

Answer 12

The first part indicates the number of carbon atoms it has. The second part indicates which homologous series the molecule belongs to

Question 13

What is a homologous series

Answer 13

A family of compounds with the same general formula and similar chemical properties

Question 14

What is fractional distillation

Answer 14

A method uses to separate miscible liquids with different boiling points

Question 15

What needs to occur for crude oil to be useful

Answer 15

The hydrocarbons it contains have to be separated: this is done through fractional distillation at an oil refinery as the hydrocarbons have different boiling points

Question 16

What is a fraction

Answer 16

A mixture of molecules with similar boiling points

Question 17

What does fractional distillation separate the hydrocarbons into when separating crude oil

Answer 17

Into fractions, in each fraction the hydrocarbons contain a similar number of carbon atoms.

Question 18

How is fractional distillation used to separate crude oil

Answer 18

The crude oil is heated and vaporised (evaporated). The vaporised crude oil enters the fractionating tower which is hotter a the bottom and cooler at the top. The hydrocarbons cool as they rise up the tower and condense at different heights because they have different boiling points. Hydrocarbons with large molecules are collected as liquids near the bottom of the tower while those with small molecules collect at the top. Therefore this process separates the hydrocarbons into fractions.

Question 19

What two changes of state does fractional distillation experience of crude oil

Answer 19

Evaporation (of crude oil)
Condensation (of fractions)

Question 20

Going from smallest molecules with lower boiling points to larger molecules with higher boiling points, explain the uses of the fractions from crude oil

Answer 20

Refinery gas for bottles gas and LPG for cars.
Petrol for vehicles
Naphtha for making chemicals
Kerosene for jet fuel
Diesel for cars and Lorries
Lubricating oil for lubricating oils
Heavy fuel oil for fuel for ships and central heating
Bitumen for roads and roofing

Question 21

Boiling point for bitumen for roads and roofing

Answer 21

350°C

Question 22

Boiling point for refinery gas for bottles gas and LPG (liquefied petroleum gases) for cards

Answer 22

25°C

Question 23

What huge industry deals with fractional distillation of crude oil and provides fuels and other substances from crude oil

Answer 23

The petrochemical industry

Question 24

Main use of hydrocarbons from crude oil

Answer 24

As fuels such as petrol kerosene or diesel

Question 25

Why are hydrocarbons good fuels

Answer 25

Because they release a lot of energy when they burn

Question 26

When does complete combustion take place

Answer 26

If there is a good supply of oxygen from the air

Question 27

What happens during complete combustion of a hydrocarbon

Answer 27

The carbon atoms are oxidised to from carbon dioxide and the hydrogen atoms are oxides to form water

Question 28

Word formula for complete combustion of a hydrocarbon

Answer 28

Hydrocarbon + oxygen -> carbon dioxide + water

Question 29

How to wring balances equation for the complete combustion of alkanes

Answer 29

1. Balance the the C atoms 2. Balance the H atoms 3. Count the number of O atoms in the CO2 and H2O and the number of O2 molecules will be half this number 4. It the number O2 molecules has a half in it, double all the balancing numbers to get rid of the half

Question 30

Definition of flammability

Answer 30

How easily a substance catches fire

Question 31

Definition of viscosity

Answer 31

How easily a liquid flows - the higher the viscosity the less easily it flows

Question 32

Example of a liquid with high viscosity

Answer 32

A slot moving liquid such as syrup

Question 33

How do properties change as you go from small hydrocarbons to large hydrocarbons

Answer 33

The boiling points increase Viscosity increases Flammability decreases Volatility decreases

Question 34

Properties of small hydrocarbons

Answer 34

Low boiling points Runny Easy to ignite More volatile

Question 35

Properties of large hydrocarbons

Answer 35

High boiling points Viscous Hard to ignite Less volatile

Question 36

Why are shorter hydrocarbons more in demand for fuels

Answer 36

Because they flow more easily, are more flammable, evaporate more easily, have a lower boiling point and burn with a cleaner flame.

Question 37

Example of large hydrocarbons that is still used as fuel

Answer 37

Fuel oil in ships and in some central heating systems

Question 38

What is cracking

Answer 38

The thermal decomposition of long hydrocarbons (alkanes) into shorter alkanes and alkanes

Question 39

What do we need cracking

Answer 39

Because shorter hydrocarbons (alkanes) are in a very high demand but the longer ones are in less demands. This means that there is a surplus of the longer hydrocarbons from the fractional distillation of crude oil. So these longer alkanes can be broken down into more useful shorter molecules which are more in demand.

Question 40

What can the alkenes produced in cracking be used for

Answer 40

A starting material to make many other substances such as polymers and medicines

Question 41

Are alkanes saturated

Answer 41

No they are unsaturated hydrocarbons

Question 42

What are the two different types of cracking

Answer 42

Catalytic cracking Steam cracking

Question 43

What is catalytic cracking

Answer 43

Heating the alkanes to vaporise them and then pass them over a hot catalyst

Question 44

What is steam cracking

Answer 44

Heat the alkanes to vaporise them, mix them with steam and then heat them to a very high temperature

Question 45

What are alkenes

Answer 45

A homologous series of undaturated hydrocarbons with the general formula CnH2n

Question 46

Formula for alkenes

Answer 46

CnH2n

Question 47

Why are alkenes in satires

Answer 47

Because they contain a carbon-carbon double bond

Question 48

Why is there no alkene with one carbon atom

Answer 48

Because at least two carbon atoms are needed in alkenes as they all contained the carbon-carbon double bond

Question 49

What are more reactive alkenes or alkanes and why

Answer 49

Alkenes are more reactive than alkanes, because they contain a carbon-carbon double bond.

Question 50

What can be used to test for alkenes and why

Answer 50

Bromine (Br2) react readily with alkenes. The carbon-carbon double bond opens up and one bromine atoms adds onto each of the carbon atoms in the double bond opens

Question 51

Learn the visual presentation of reaction of bromine (br2) with alkenes

Question 52

What does the reaction of bromine used to test for

Answer 52

The presence of C=C carbon double bonds in compounds

Question 53

How to test for C=C double bonds

Answer 53

Bromine water, a solution of bromine in water and is a clear, orange coloured solution due to the dissolved Br2 molecules, is reacted with a substance you are trying to test. If the substance is a saturated compound with no C=C double bonds then the solution stays orange however if it is unsaturwd and contains C=C double bonds then it goes from an clear, orange coloured to colourless.

Question 54

Example of alkenes producing polymers

Answer 54

Many subunits (monomers) of ethene can be linked together to form polyethene (polythene)

Question 55

What is volatility

Answer 55

How easily it is evaporated (

Question 56

Example of high volatile liquid

Answer 56

Perfume