Alkenes

Question 1

are alkenes saturated or unsaturated

Answer 1

unsaturated

Question 2

what is an unsaturated hydrocarbon

Answer 2

containing carbon carbon double bonds

Question 3

is a pi bond stronger or a sigma bond

Answer 3

sigma bond is stronger

Question 4

when alkenes react what type of bond breaks first

Answer 4

pi bond

Question 5

what happens in the addition reaction of an alkene

Answer 5

the pi bond breaks and new atoms or groups are added to for a single product

Question 6

what is an electrophile

Answer 6

an electron pair acceptor ( attracted to regions of high electron density)

Question 7

why do alkenes attract electrophiles

Answer 7

they have a C=C which is an area of high electron density

Question 8

what are the different electrophilic addition reactions that alkenes go through

Answer 8

• reaction with bromine ( and other halogens)
• reaction with hydrogen halides
• reaction with conc sulfuric acid
• reaction with water

Question 9

reaction with bromine allows us to test for unsaturation in hydrocarbons. What happens when bromine water is added to an alkene

Answer 9

Br2 water is decolourised (goes from and orange brown solution to a colourless solution)

Question 10

what type of species is formed in the intermediate reaction when an alkene reacts with bromine

Answer 10

carbocation

Question 11

why does the secondary carbocation form the major product over the primary carbocation

Answer 11

it is more stable due to having more e- releasing alkyl groups

Question 12

conditions needed for the reaction of alkenes with H2SO4

Answer 12

cold conc H2SO4

Question 13

conditions needed for the reaction between alkenes and water

Answer 13

H3PO4 catalyst, 70 atm, high temp (300 degrees)

Question 14

Alkenes + H2O

Answer 14

alcohols

Question 15

what can alkyl hydrogen sulphates be further reacted with H2O to form

Answer 15

alcohols

Question 16

how do alkenes undergo polymerisation to form a polymer chain

Answer 16

pi bond breaks and the e- pair is used to form a bond with a C atom on a neighbouring molecule

Question 17

what type of polymerisation do alkenes undergo

Answer 17

addition polymerisation

Question 18

what catalyst is required to bring about polymerisation

Answer 18

Zeigler - Natta catalyst

Question 19

advantages of landfill

Answer 19

easy
quick
cheap

Question 20

disadvantages of landfill

Answer 20

limited space
not sustainable
eyesore

Question 21

advantages of incineration

Answer 21

reduced waste
effective disposal

Question 22

disadvantages of incineration

Answer 22

releases harmful products such as CO2
greenhouse effect

Question 23

advantages of recylcing

Answer 23

sustainable
conserves natural resources
less waste

Question 24

disadvantages of recylcing

Answer 24

expensive
time consuming