alkenes

Question 1

describe the reaction of alkenes and steam?

Answer 1

alkenes react with steam in the presence of phosphoric acid to form alcohols

Question 2

what is an electrophile?

Answer 2

an electron pair acceptor

Question 3

why are alkenes more reactive than alkanes?

Answer 3

1. the pi electrons are more exposed

2. pi bond enthalpy is weaker

Question 4

what is the mechanism of electrophilic addition by heterolytic fission?

Answer 4

1. bonded pair in the electrophile moves to one of the bonded atoms to form two ions
2. lone pair from bromide ion moves to cation
3. this forms the product

Question 5

what is Markownikoff’s rule?

Answer 5

the hydrogen will join the carbocation with the most hydrogens on it

Question 6

describe addition polymerisation

Answer 6

1. the pi bond in a monomer breaks

2. these monomers bond with others

Question 7

What are the benefits of burning waste polymers?

Answer 7

1. Can be used for energy production

2. Requires treatment of potentially harmful gases

Question 8

what are the benefits and risks of burning polymers?

Answer 8

1. their incineration can be used to produce energy

2. there are potentially harmful emissions from their combustion

Question 9

what are the risks and benefits of feedstock recycling?

Answer 9

1. breaks down polymers to starting materials that can be recycled
2. the process is uneconomic

Question 10

what are the risks and benefits of PVC recycling?

Answer 10

1. when toxic waste products are removed, it can be a good way to recycle
2. it is hazardous due to the high chlorine content and other hazardous emissions

Question 11

what are the risks/benefits of bio/photodegradable plastics?

Answer 11

1. highly sustainable as they degrade naturally and leave no waste
2. not as widely useful beyond shopping bags

Question 12

what is the c=c bond?

Answer 12

the sideways overlap of p orbitals over an overlap of s orbitals. restricts rotation

Question 13

what shape and bond angle around each carbon in a c=c double bond?

Answer 13

1. trigonal planar
2. 120 degrees
   no free e- pairs to repel further

Question 14

what is a stereoisomer?

Answer 14

same structural formula but different arrangement in space

Question 15

what does E/Z isomerism mean?

Answer 15

two different groups attached to each carbon atom of the c=c bond

Question 16

what is cis-trans isomerism?

Answer 16

where two of the substituent groups attached to the carbon atoms are the same