Alkenes

Question 1

What is an alkene?

Answer 1

An unsaturated hydrocarbon with a carbon carbon double bond

Question 2

How can you make alkenes?

Answer 2

Cracking

Elimination of halogenoalkanes

Question 3

What is the general formula for alkenes?

Answer 3

CnH2n

Question 4

What is the test for unsaturation?

Answer 4

Bromine water makes alkenes go from orange to colourless

Question 5

What causes E-Z isomerism?

Answer 5

Restricted rotation around the double bond

Question 6

What is stereoisomerism?

Answer 6

When molecules have the same structural formula but the atoms/groups have a different arrangement in 3D space

Question 7

What is EZ isomerism?

Answer 7

When molecules have the same structural formula but a different arrangement of atoms in 3D space around a double bond

Question 8

What are isomers?

Answer 8

Molecules with the same molecular formula but a different structural formula

Question 9

What is addition polymerisation?

Answer 9

When alkenes react together to form addition polymers

Question 10

What is a monomer?

Answer 10

The unit which breaks its double bond and forms polymers

Question 11

What is a polymer?

Answer 11

A long chain of repeating monomer units joined together

Question 12

What are the two types of poly(ethene)

Answer 12

Low density poly(ethene) and high density poly(ethene)

Question 13

What are the conditions under which LDPE is made?

Answer 13

200 degrees celcius, 120000kPa with little oxygen

Question 14

Describe the structure of LDPE

Answer 14

Branched chains which don’t pack closely together and softens at temps below 100

Question 15

What are the conditions under which HDPE is made?

Answer 15

60 degrees celcius, titanium chloride catalyst

Question 16

Describe the structure of HDPE

Answer 16

Straight chains which can pack more tightly together. Softens at higher temperatures

Question 17

What is PVC?

Answer 17

poly(chloroethane)

Question 18

How is PVC made softer?

Answer 18

Plasticiser which makes it more flexible

Question 19

What bonds hold monomers together?

Answer 19

Covalent bonds

Question 20

What bonds hold polymer molecules together?

Answer 20

Van der Waals forces

Question 21

What are the problems with polymers?

Answer 21

Not biodegradable, take years to decompose, platic liter can be ingested by animals, non-renewable oil and if incinerated it produces toxic CO2 gas

Question 22

What are electrophiles?

Answer 22

Electron pair acceptors

Question 23

Why do electrophiles attack double bonds?

Answer 23

Bc they’re areas of high electron density

Question 24

In electrophilic addition with bromine, what are the conditions?

Answer 24

Alkenes
Bromine
Room temp
No light

Question 25

In the electrophilic addition with hydrogen bromide, what are the conditions?

Answer 25

Heat under reflux, alkenes, phosphoric (V) acid catalyst and sodium halide

Question 26

When can more than one product be formed from electrophilic addition?

Answer 26

When the alkene is unsymmetrical

Question 27

What is the most stable product in any electrophilic addition and why?

Answer 27

The one with more alkyl groups attached, bc alkyl groups have a positive inductive effect which pushes electrons towards the carbocation and stabilises its charge

Question 28

What is Markovnikov's rule?

Answer 28

The hydrogen halide adds on so that the hydrogen atom adds to the carbon which already has the most hydrogens

Question 29

What is a carbocation?

Answer 29

A species which contains a positive charge on the carbon atom

Question 30

What is an addition reaction?

Answer 30

A reaction in which two molecules join together to make one larger molecule

Question 31

What is heterolytic fission?

Answer 31

When a covalent bond break and both electrons in the bond move to one of the atoms

Question 32

What are the conditions needed for the electrophilic addition with sulfuric acid?

Answer 32

concentrated sulfuric acid, alkene and room temp

Question 33

What are the conditions needed in hydration?

Answer 33

Stean, pressures of 60atm and 600K and a concentrated strong acid catalyst

Question 34

What is the functional group of alkenes?

Answer 34

C=C

Question 35

What is uPVC used for?

Answer 35

Window and door frames and drainpipes

Question 36

What is PVC used for?

Answer 36

Clothing and wellington boots