chemistry model 2.1

Question 1

Why can carbon form so many compounds?

Answer 1

• Can form bond to the other carbon atoms to make chains and rings
• Can form single, double, triple bonds to another carbon atom
• Can bond with elements

Question 2

What are hydrocarbons?

Answer 2

Organic compounds consisting of hydrogen and carbon atoms only

Question 3

What is a saturated hydrocarbon?

Answer 3

Hydrocarbon single bonds only

Question 4

What is an unsaturated hydrocarbon?

Answer 4

Hydrocarbon containing carbon to carbon multiple bonds

Question 5

What is aliphatic hydrocarbon?

Answer 5

Hydrocarbon of carbon atoms joined together in straight or branched chains

Question 6

What is an alicyclic hydrocarbon?

Answer 6

Hydrocarbon With carbon atoms joined together in a ring structure

Question 7

What is a functional group?

Answer 7

Part of the organic molecule responsible for chemical reactions

Question 8

What is a homologous series?

Answer 8

A series of organic compounds consisting of the same functional group but with each successive member differing By CH2

Question 9

What are alkanes?

Answer 9

Homologous series with the general formula CnH2n+2

Question 10

What is nomenclature?

Answer 10

System of naming compounds

Question 11

What is the general formula for an alkene?

Answer 11

CnH2n

Question 12

What is the general formula for an alcohol?

Answer 12

CnH2n+1OH

Question 13

What are the three ways structural isomerism can occur?

Answer 13

• Hydrocarbon chain can be branched or unbranched
• Functional groups can be in different positions
• Functional groups can be different

Question 14

What are structural isomers?

Answer 14

Molecules of the same molecular formula but with different structural arrangement of atoms

Question 15

What are stereoisomers?

Answer 15

Compounds of the same structural formula but different arrangement of atoms in space

Question 16

What are the 2 types of stereoisomerism?

Answer 16

E/Z isomerism

Cis-trans isomerism

Question 17

What are the two ways a covalent bond can be broken?

Answer 17

Homolytic fission

Heterolytic fission

Question 18

What is homolytic fission?

Answer 18

• Each bonded atom takes one of the shared pair of electrons and each atom is now called a radical
• 2 species of the same type are produced

Question 19

What is heterloytic fission

Answer 19

• One of the atoms takes both of the electrons and each atom becomes an ion
• The one that takes the electrons is an anion and the one that gives the electrons is a cation

Question 20

What is an addition reaction?

Answer 20

The reaction where a reactant is added to an unsaturated molecule to make a saturated molecule

Question 21

What is a substitution reaction?

Answer 21

A reaction where an atom or group of atoms is replaced with another atom or group of atoms

Question 22

Explain how fractional distillation works?

Answer 22

• Crude oil vaporised by heating and then passed into Column
• Gas is passed through the column until it gets to a compartment with a lower Temperature than the boiling point
• Condenses and then turns into liquid where tapped off into storage containers

Question 23

How is the boiling points of alkanes affected by chain-length?

Answer 23

Short chain hydrocarbons have a lower boiling point and condense near the top of the column whereas long chain hydrocarbons have a higher boiling point and condense near the bottom of the column

Question 24

Define fractional distillation?

Answer 24

Separation of the components in a liquid mixture into

fractions which differ in boiling point by means of distillation, using a fractionating column

Question 25

How does branching affect boiling point about alkanes?

Answer 25

-More branching means fewer points of contact which means less Vanderwall forces which means lower temperature is needed to break the Vanderwall forces, also molecules cannot get close to each other as Unbranched ones decreasing inter molecular forces between the molecules

Question 26

What does complete combustion born? | What does incomplete combustion form?

Answer 26

CO2 + H2O | CO + H2O

Question 27

How can branched alkanes be produced? | How can cyclic hydrocarbons be produced?

Answer 27

Isomerisation | Reforming

Question 28

What is elimination reaction?

Answer 28

One reactant reacts to form 2 products | A molecule is removed from a saturated to make an unsaturated molecule

Question 29

Why are short chain alkanes valuable as clean fuels?

Answer 29

They burn in a plentiful supply of oxygen to form carbon dioxide and water

Question 30

Define cracking?

Answer 30

The breaking down of long chain saturated hydrocarbons to form a mixture of short chain alkanes alkenes

Question 31

Why are short chain hydrocarbons in high demand?

Answer 31

- for use as fuels | - to use in polymer production

Question 32

What is the hydrogen that is produced During reforming used for?

Answer 32

Making margarine | The production of ammonia

Question 33

Name some examples of petrochemicals?

Answer 33

Ink, dye, fuel, plastics, pharmeucuticals

Question 34

What harmful byproducts does the burning of hydrocarbons produce?

Answer 34

Carbon monoxide Carbon dioxide Nitrogen oxides Sulfur dioxide

Question 35

Name two examples of agricultural crop specifically grown for energy use ?

Answer 35

Sugar cane in brazil | Rape in english countryside

Question 36

Why is ethanol a good example of a biofuel?

Answer 36

Burns efficiently in oxygen to produce CO2 and water Can be mixed with petroleum for efficient fuel burning Can be used in car engines without major modifications

Question 37

Define radical substitution?

Answer 37

Substation reaction where a radical replaces a different atom or group of atoms

Question 38

Define mechanism?

Answer 38

Sequence of steps showing the paths taken by electrons in a reaction

Question 39

Define initiation?

Answer 39

The first step in a radical substitution in which the free radicals are generated by UV radiation

Question 40

What happens in the initiation stage of a radical substitution reaction?

Answer 40

Covalent bond is broken by homolytic fission to form 2 radicals

Question 41

What happens in propogation?

Answer 41

Free radical reacts with alkane to make a alkyl and a by product Alkyl then reacts with a complete new molecule E.G. CH4 + Cl• ➡ •CH3 + HCl •CH3 + Cl2 ➡ CH3Cl + •Cl

Question 42

What happens in termination

Answer 42

Two radicals combine to form a molecule E.G •Cl + •Cl ➡ Cl2 •CH3 + •CH3 ➡ C2H6

Question 43

What protect the body from free radicals?

Answer 43

Antioxidants such as vitamin C and E

Question 44

What is a nucleophile?

Answer 44

An atom or group of atoms that is attracted to an electron deficient centre where it donates a pair of electrons to form a new covalent bond

Question 45

What is an electrophile?

Answer 45

An atom or group of atoms that is attracted to the electron rich centre where it excepts a pair of electrons to form a new covalent bond

Question 46

How are polymers used as a fuel source?

Answer 46

Burned to produce heat energy which can be harnessed for electricity

Question 47

What is synthesis gas and what can it be used for?

Answer 47

Mixture of hydrogen and carbon monoxide | Can be used as a chemical feedstock for conversion into fuel or other useful products

Question 48

Why would it be helpful to be able to convert common household plastics into organic materials

Answer 48

Better than them being disposed of in landfill sites

Question 49

Why is polu vinyl chloride problematic

Answer 49

High chlorine content and is uneconomical as recycling is more expensive than the crude oil itself

Question 50

Why is incineration of PVC not useful

Answer 50

- Burns to form toxic fumes into the environment and corrodes the plant itself - High temps associated with acidic hydrogen chloride fumes

Question 51

What do bioplastics degrade into

Answer 51

water and carbon dioxide, inorganic compounds and biomass

Question 52

Name some biodegradable things

Answer 52

bags made from biodegradable material such as plant starch disposable tableware made from sugar cane fibre poly(lactic acid) in cold drink cups

Question 53

What happens when an alkene reacts in terms of pi-bonds and sigma bonds

Answer 53

- a small molecule is added across the double bond to break the pi bond - the pi bond breaks and the sigma bond remains intact

Question 54

What are the conditions of water added to an alkene

Answer 54

it is present as steam | done under an acid catalyst