Organic Analysis

Question 1

Test for alcohols

Answer 1

Primary and secondary alcohols identified using acidified potassium dichromate. It turns from orange to green. Tertiary alcohols are not oxidised so remain orange.

Question 2

Test for aldehydes

Answer 2

Tollen’s reagent forming silver mirror or stay colourless if not present. Fehling’s solution added and heated to form brick red precipitate or remains blue if not present.

Question 3

Test for alkenes

Answer 3

Bromine water goes from orange-brown to colourless

Question 4

Test for carboxylic acid

Answer 4

Sodium carbonate added to produce CO². Can be collected and tested using limewater. Solution turns cloudy if the gas is CO².

Question 5

Fingerprint region on IR

Answer 5

Each IR spectrum has a fingerprint region to the right-hand side. This contains tiny differences from species to species which act as a molecules fingerprint allowing it to be identified.

Question 6

Global warming info

Answer 6

IR also occurs in the atmosphere with molecules such as ozone. This causes heat to be trapped within the atmosphere.