2.6 Halogenoalkanes

Question 1

what 2 mechanisms do you need to know

Answer 1

nucleophilic substitution
nucleophilic addition

Question 2

which mechanism is used to prepare alcohols from halogenoalkanes

Answer 2

nucleophilic substitution

Question 3

what is the nucleophile OH- provided from in nucleophilic substitution

Answer 3

aqueous sodium hydroxide

Question 4

what is reflux?

Answer 4

a process of continuous evaporation and condensation

Question 5

why is the solution refluxed during preparation of an alcohol

Answer 5

mixture is heated to speed up process. Reflux stops too much liquid from evaporating and escaping

Question 6

what are the differences when using different halogens

Answer 6

• electronegativity
• bond strength

Question 7

which halogenoalkane will be hydrolyzed most rapidly

Answer 7

iodo>bromo>chloro

iodo fastest

Question 8

what test is used to differentiate the halogen in halogenoalkanes

Answer 8

addition of Ag+

Question 9

what colour ppt is present when Ag+ is added to chlorine

Answer 9

white ppt

Question 10

what colour ppt is present when Ag+ is added to bromine

Answer 10

cream ppt

Question 11

what colour ppt is present when Ag+ is added to iodine

Answer 11

yellow ppt

Question 12

name 3 uses of halogenoalkanes

Answer 12

1. solvents
2. anesthetics
3. Refrigerants

Question 13

what is the ozone layer

Answer 13

a layer surrounding the earth that contains O2 molecules

Question 14

what are CFCs

Answer 14

halogenoalkanes which contain chlorine + fluorine

Question 15

what are HFCs

Answer 15

halogenoalkanes which contain only fluorine

Question 16

why were uses of halogenoalkanes regulated

Answer 16

• CFCs cause damage to the ozone layer (and are toxic)
• holes in ozone layer cause increase of skin cancer.

Question 17

what alternatives to CFCs are there

Answer 17

HFCs