Tests for Functional Groups

Question 1

For 1y/2y/3y alcohols

Answer 1

10 drops of alcohol to 2 cm^3 acidified potassium dichromate
warm gently i hot water bath
orange turns green for 2y/1y alcohols
no change for 3y

Question 2

for 1y/2y FEHLINGS

Answer 2

Add 2cm^3 Fehling's/Benedicts solution to test tube
add 5 drops of unknown
warm in hot water bath
aldehyde gives brick red precipitate
ketone does nothing

Question 3

1y/2y TOLLENS

Answer 3

2cm^3 of 0.1M silver nitrate solution
add dilute sodium hydroxide drops - light brown ppt formed
add dilute ammonia solution drops - ppt dissolves completely
warm in hot water bath
add 10 drops of unknown
aldehyde gives silver mirror/test tube coated with silver
ketone does nothing

Question 4

Alkenes

Answer 4

Bromine water
2cm^3 unknown solution to test tube
add 2cm^3 of bromine water and shake
alkene - solution orange to colourless (alCLEAN lol)
not alkene does nothing

Question 5

Carboxylic acids

Answer 5

2cm^3 solution unknown plus 1 small spatula of NaCO3(s)
if fizzing occurs, bubble gas through limewater in second test tube
carboxylic acid will fizz. gas produced will turn limewater cloudy
not COOH does nothing