Alkenes Ch5

Question 1

Bonding

Double bond formation

Answer 1

a sigma and pi bond
pi bond above and below the sigma bond

Question 2

Shape

Shape and angle of double bond

Answer 2

Trigonal Planar + 120

Question 3

Definition

Steroismerism

Answer 3

Molecules with some structural formula , but a different arrangement in sapce / 3D arrangement

Question 4

Steroismerism

Geometric

Answer 4

Restricted rotation around the C=C bond
Must have 2 different atoms or groups of atoms

Question 5

Cis/trans nameing

Cis - Alkenes

Answer 5

the Alkyl groups are on the same side (either both above or both below the double bond)

Question 6

Cis/trans nameing

trans - alkenes

Answer 6

the alkyl groups are of opposite sides (one above, one below the double bond )

Question 7

E/Z namig

E isomer

Answer 7

Trans- is this isomer
Use the atomic mass, the heaiver atoms on each side
opposite sides of the double bond

halogenalkenes

Question 8

E/Z Naming

Z isomer

Answer 8

cis- is this isomer
use atomic mass to find heavier side
same side of the double bond

halogenalkenes

Question 9

Testing for unsaturation

Bromine

Br2

Answer 9

Brown to colourless
Addition reaction

Question 10

Testing for undsaturation

Bromine water

Br2 + H2O

Answer 10

orange to colourless
creates HBr

Question 11

Reactions of Alkenes

Hydrogen

Answer 11

Hydrogenation reaction
NIckel Catalyst
Alkenes + H2 –> Alkane

Question 12

Reactions of Alkenes

Halogen

Answer 12

Halogenation
Alkenes + halogen –> dihalogenalkane

Question 13

Reactions of Alkenes

Hydrogen Halide

Answer 13

Alkenes + Hydrogen Halide –> halogenalkane

Question 14

Reactions of Alkenes

With steam

Hot H2O (g)

Answer 14

ALlkenes + H2O (g) –> Alcohol
Phospheric acid (H3PO4) Catalyst
100% atom economy

Question 15

Reactions of Alkenes

Oxidation to produce a diol

Contains 2 -OH groups

Answer 15

Alkene + Oxisiding agent + H2O –> Alkane diol

Potassium maganate (KMnO4)
Purple to colourless

Question 16

Electrophilic Addition Reactions

Ethene + bromine

Answer 16

Double bond very reactive
Hetrolytic Fission
Carbocatio is formed
Br+ is the electrophile

Question 17

Electrophilic Addition Reactions

With HBr

Answer 17

Ethene symmetrical reacts to form bromoethane an asymmetrical

Question 18

Electrophilic Addition Reactions

Propene + hydrogen Bromide

Answer 18

Both molecules are asymmetrical
2-bromopropane major product
-seconday carbocation formed in the mechanism when H bonds to the Carbon 1 is more stable than if a primary carbocation was formed

Question 19

Definition

Addition Polymerisation

Answer 19

The joining together of many small monomers to produce a long chain through the breaking of a C=C double bond

Question 20

Polymer waste

Answer 20

1. Land fill (they don’t decompose)
2. Recycling (sorted by type and remoulded)
3. Combustion (Provides energy / gases could be toxic )

Question 21

Biodegradeable polymers

uses, disadvantages and source

Answer 21

Corn or starch
uses : compostable cups and cutley
Disadvantages: Needs lots of land
C & H produced on teh reak down cannot be used directly