Testing for functional groups:

Question 1

How to test for alkenes and alkanes?

Answer 1

= add bromine water (orange solution)
= alkene present: orange solution turns colourless
= alkane present: remains an orange solution

Question 2

How to identify haloalkanes?

Answer 2

= warm with dilute sodium hydroxide solution
= add acidified nitric acid, silver nitrate solution
= add dilute ammonia and add concentrated ammonia

Question 3

How do we identify alcohols?

Answer 3

= warm with orange acidified pottasium dichromate solution
= orange should turn green: primary and secondary alcohol
= remains orange solution for teritary alcoghols

Question 4

How to test for aldehydes?

Answer 4

= warm aldehyde with fehlings solution, this is a blue solutionaHow to test for aldehydes?
= the blue solution should turn a red precipitate- contains cu2+ ions

= warm aldehyde with tollens reagant, silver mirror is formed inside the test tube

Question 5

How to identify carboxylic acids?

Answer 5

= limewater
= add carbonate and bubble the gas produced in limewater
= efferscence is produced, bubbling through water makes it cloudy

Question 6

What is tollens reagant made from?

Answer 6

= mixing aq ammonia and silver nitrate
= (Ag(NH3)2)+
= silver ions Ag+ are reduced to Ag atom
=

Question 7

What happens in fehlings reagant?

Answer 7

= copper 2+ ions are reduced to copper (I) oxiden