Alkenes

Question 1

Monomer

Answer 1

Small molecules that combine with many other monomers to form a polymer

Question 2

Addition polymerisation

Answer 2

Formation of polymers from many monomers joining together

With no other products formed

Question 3

Electrophile

Answer 3

Electron pair acceptor

Question 4

Describe the electrophoretic addition to alkenes mechanism

Answer 4

Slightly positive part of another molecule attracts electron pair form double bond

Double bond breaks and +/ve joins molecule

Negative ion left

Alkene becomes carbocation

Anion gives electrons to +/ve Carbon on carbocation

Question 5

Hydrogenation

Answer 5

Addition of hydrogen to alkenes with nickel catalyst

Breaks double bond to form alkane

Question 6

Stereoisomers

Answer 6

Same molecular and structural formulae

Different arrangement of atoms in space

Question 7

Z isomer

Answer 7

Heavier groups on the same side

Question 8

E isomers

Answer 8

Heavier groups on different sides of the molecules

Question 9

Polymer

Answer 9

Long chain molecule formed from small molecules joined together

Question 10

Describe bonding of alkene (3)

Answer 10

• 3 bonding regions: 3BP 0 LP
• double bond formed by sigma and pi bond which is the overlapping of 2 p orbitals
• pi has low AVE, making alkenes Iess reactive
• No rotation around the bond due to high electron density concentration which fixes the atoms in place.

Question 11

Shape of alkenes

Answer 11

• trigonal planar: atoms are in the same plane
• 3 electron density regions around double bond repel equally
• 3BP and 0LP

Question 12

Problems with polymers (2)

Answer 12

• has to be sorted and washed to recycle

- PVC releases toxic gases when burned

Question 13

Solutions to recycling polymers (7)

Answer 13

• can make new products and preserve crude oil source
• burned to produce new energy
• saves fossil fuels
• solvents dissolve PVC so it does not have to be burned
• photodegradable
• biodegradable
• feedstock recycling

Question 14

Photodegradable

Answer 14

• some bonds are weakened by light in polymers. No need to heat

Question 15

Biodegradable polymers (2)

Answer 15

• can be broken by microorganisms into CO2 and H20

- eg Starch and cellulose

Question 16

Feedstock recycling of polymers (2)

Answer 16

• using heat to transform polymers into monomers

- instead of washing waste polymers

Question 17

E/Z isomerism. (3)

Answer 17

• Stereoisomers: each carbon in double bond has to have different groups attached
• E: when high prioritised atoms are on different sides; diagonally across the double bond.
• Z: high prioritised atoms on the same side (Zame Zide) of the double bond

Question 18

Cis-Trans isomerism.

Answer 18

• Similar to E/Z where each atom bonded to the double bond carbon has to be different
• However one of the bonded atoms to the Carbon on the double bond has to be Hydrogen
• Cis: Hydrogen on the same side of double bond (Z)
• Trans: Hydrogen diagonally across double bond (E)

Question 19

Stereoisomers (2)

Answer 19

• Molecules with the same molecular AND structural formulae.

- Different arrangement of atoms in space.

Question 20

Process of turning Alkene to alkane?

Answer 20

• Hydrogenation (electrophliic addition)

- Nickel catalyst and hydrogen

Question 21

Alkene to haloalkane (2))

Answer 21

• Electrophilic addition

- Alkene + Halogen/ Hydrogen Halide

Question 22

Alkene to alcohol (3)

Answer 22

• Hydrolysis (electrophilic addition)
• Alkene + steam under high heat
• H3PO4 catalyst