3.3.1 and 3.3.2 Alkenes

Question 1

Alkenes

General formula

Answer 1

CnH2n

Question 2

Alkenes made up of

Answer 2

hydrocarbons

Question 3

Alkenes are

saturated or unsaturated?

Answer 3

unsaturated

Question 4

Alkenes

Answer 4

Unsaturated hydrocarbons with double bonds between one or more of the carbon atoms.

Question 5

Alkenes reactivity?

why

Answer 5

pretty reactive

due to 2 pairs of e-s in the double bond so high e- density

Question 6

Electrophilic addition reactions

Answer 6

double bonds open up and atoms are added to the carbon atoms

Question 7

Why does electrophilic addition occur

Answer 7

plenty of electrons in the double bond so easily attacked by electrophiles

Question 8

Electrophiles are …

Answer 8

electron pair acceptors

Question 9

What are electrophiles attracted to

2

Answer 9

negative charge

polar molecules

Question 10

Electrophile

definition

Answer 10

Lone pair acceptors

Question 11

Addition

definition

Answer 11

Reaction which increases the number of substituents

Question 12

Test for alkenes

Answer 12

bromine water test

Question 13

Bromine water test

Answer 13

Add an alkene to bromine water in a test tube with a bung
shake
if the solution goes from orange to colourless an alkene is present

Question 14

How does the bromine water test work

Answer 14

bromine is added across the c=c bond making a dibromoalkane which is colourless
electrophilic addition

Question 15

Halogenoalkanes formed by

Answer 15

alkenes and hydrogen halides (eg: HBr)

electrophilic addition

Question 16

Carbocation intermediate

Answer 16

Amount of each product formed depends on how stable the carbocation formed in the middle of the reaction is

Question 17

Carbocation?

Answer 17

a molecule with a carbon atom which has 3 bonds and a positive charge

Question 18

Unsymmetrical alkene with hydrogen halide

Answer 18

carbocation intermediate
or
more stable carbocations (with more alkyl groups)

Question 19

Carbocations with more alkyl groups

Answer 19

are more stable

Question 20

Alkyl groups

Answer 20

alkanes with with a hydrogen removed

eg: methyl CH3-

Question 21

Alkenes reactions with H2SO4

Answer 21

alkenes react with cold, concentrated sulphuric acid to form alkyl hydrogen sulfates

Question 22

How to convert alkyl hydrogen sulphates into alcohol

Answer 22

add water and warm the reaction mixture

Question 23

reaction with an unsymmetrical alkene

Answer 23

mixture of products