Identifying Organic Compounds

Question 1

Bromine water Br2 (aq)

Answer 1

an orange-brown liquid that is decolourised rapidly by alkenes (addition reaction forming dibromohexane) and alkynes but only very slowly by alkanes

Question 2

acidified pottasium permanganate H+/MnO4-

Answer 2

a purple liquid that if heated with primary alcohol becomes colourless as it oxidised the alcohol (to a ketone-carboxylic acid)
if added to an alkene (no heat required) also becomes colourless as it oxides the alkene (forms a diol)

Question 3

acidified potassium dichromate H+/Cr2O72-

Answer 3

an orange liquid that if heated with a primary alcohol becomes green as it oxides the alcohol (redox/oxidation reaction)

Question 4

carbonates or hydrogen carbonates (Na2CO3 or NaHCO3)

Answer 4

these bases will neutralise a carboxylic acid releasing CO2 gas (seen as bubbles) (acid-base reaction)

Question 5

blue litmus paper

Answer 5

carboxylic acids turn blue litmus paper red

Question 6

red litmus paper

Answer 6

amines turn red litmus blue

Question 7

solubility test in water

Answer 7

hydrocarbons and haloalkanes in water form two layers (are insoluble) short chain (C1-4) alcohols, carboxylic acids and amines are soluble in water

Question 8

smell test

Answer 8

carboxylic acids have a sharp acidic smell like viegar, amines have a distinctive fishy smell