Organic chemistry

Question 1

What is crude oil made up of?

Answer 1

• mixture of lots of different compounds which are not chemically bound
• made up of hydrocarbons

Question 2

What is crude oil made from?

Answer 2

-fossilised remnants of ancient plankton

Question 3

What are long chain hydrocarbons?

Answer 3

-hydrocarbons with lots of carbon atoms

Question 4

What is the purpose of fractional distillation?

Answer 4

-separates different hydrocarbons using different boiling points

Question 5

List the steps of fractional distillation.

Answer 5

1) evaporate the crude oil by heating it and the vapour is put into a fractionating column
2) condensation-long chain hydrocarbons condense at the bottom and are collected as liquids, short chain condense at the top
3) collection-fractions are collected and processed to make end products e.g fuel, bitumen for roads

Question 6

Uses of fractions of crude oil.

Answer 6

Bitumen
Surfacing roads and roofs
Fuel oil
Fuel for ships and power stations
Diesel Oil
Fuel for some cars and trains
Kerosene
Fuel for aircrafts
Gases
Domestic heating and cooking
Petrol
Fuel for cars

Question 7

What are some property’s of long chain hydrocarbons?(4)

Answer 7

• viscous
• darker in colour
• less flammable
• have higher boiling points

Question 8

What does the combustion of hydrocarbons result in?

Answer 8

• energy release

- the oxidisation of carbon and hydrogen to create carbon dioxide and water

Question 9

What is created if alkanes burn without oxygen?

Answer 9

-carbon monoxide

Question 10

What does incomplete combustion produce?

Answer 10

-carbon soot

Question 11

What is the problem of sulfur dioxide?

Answer 11

-it is an impurity present in all hydrocarbons
-when sulfur is burned, it produces a toxic gas=sulfur dioxide
-can react with water to make sulfuric acid which is a component of acid rain
-

Question 12

How can nitrogen oxide be produced from hydrocarbons?

Answer 12

-when hydrocarbons are burned in confined spaces the temperature rises and can cause nitrogen and oxygen to react

Question 13

What is cracking?

Answer 13

• the process that breaks down long-chain hydrocarbons into shorter-chain molecules that are more useful.
• Cracking is an example of a thermal decomposition reaction.

Question 14

How are alkanes and alkenes produced?

Answer 14

-when heavy hydrocarbons are mixed with steam in a high temperature environment

Question 15

Why do heavy fractions of crude oil not make good fuels?

Answer 15

• they don’t ignite easily
• have high boiling points
• have low volatility

Question 16

What is the homologous series?

Answer 16

-a series of compounds with the same general formula.

Question 17

What do the members in the homologous series have?

Answer 17

-have similar chemical properties, but the physical properties can change.

Question 18

What are alkanes?

Answer 18

• saturated hydrocarbons as all their bonds with other atoms are single bonds.
• they bond to four atoms

Question 19

What are some uses of alkanes?

Answer 19

• they have quite low reactivity, but they combust quite well.
• This makes them useful as fuels.

Question 20

What is the general formula of alkanes?

Answer 20

-CnH(2n+2)

Question 21

What can alkanes react with?

Answer 21

• Although alkanes are quite unreactive, they will react with chlorine in the presence of UV light. The UV light activates the chlorine molecule, which starts the reaction.
• The overall reaction is a substitution reaction, as one hydrogen atom on the hydrocarbon is replaced by chlorine.
• The products formed are a chloroalkane and hydrogen chloride.

Question 22

List the size order of alkanes,

Answer 22

Methane
Ethane
Propane
Butane
Pentane
Hexane

Question 23

What is a structural isomer?

Answer 23

-compounds with the same molecular formula, but with different structural formulas.

Question 24

What is an alkene?

Answer 24

• hydrocarbons with the functional group C=C.
• alkenes have a carbon-carbon double bond.
• unsaturated hydrocarbons because they contain a double bond between two of their carbon atoms

Question 25

What is the general formula for alkenes?

Answer 25

-CnH(2n)

Question 26

What type of reactions usually take place in alkenes?

Answer 26

• addition reactions

- In these reactions, the C=C bond opens up and allows carbon atoms to bond with new atoms.

Question 27

What is hydrogenation?

Answer 27

-adding hydrogen atoms across a C=C double bond

Question 28

What does alkene plus water yield?

Answer 28

-alcohol

Question 29

What does alkene plus oxygen yield?

Answer 29

-carbon monoxide, carbon, and water

Question 30

What does alkene plus hydrogen yield?

Answer 30

-an alkane

Question 31

What does alkene plus bromine yield?

Answer 31

-dibromoalkane (a colourless solution)

Question 32

What type of combustion do alkenes produce?

Answer 32

-incomplete

Question 33

What is a substitution reaction?

Answer 33

-when one atom is swapped with another

Question 34

What is a thermal decomposition reaction?

Answer 34

-an endothermic reaction which has one reactant

Question 35

What is an addition reaction?

Answer 35

-when one molecule combines with another molecule, forming one large molecule

Question 36

What are polymers?

Answer 36

-large, chain-like molecules that can extend for thousands of atoms

Question 37

What are polymers held together by?

Answer 37

• Strong covalent bonds between atoms in molecules.
• Weak intermolecular forces between molecules. (but because of the large size the intermolecular forces add up to be quite strong)

Question 38

What state are polymers at room temperature?

Answer 38

-solid but melt easily

Question 39

What is addition polymerisation?

Answer 39

-the joining of short-chain monomers to produce one long-chain polymer.

Question 40

Why are alkenes monomers in addition polymerisation?

Answer 40

-alkenes can open up their carbon-carbon double bonds to join together

Question 41

What is the product of addition polymerisation?

Answer 41

-the polymer

Question 42

What is the problem of disposing addition polymers?

Answer 42

• cannot biodegrade

- produce toxic gases when they are burned