3.3.6 Organic analysis

Question 1

Test for an alkene

Answer 1

Add bromine water/Br2
If alkene present goes form orange to colourless

Question 2

Test for halogenoalkanes

Answer 2

Dissolved in ethanolic solvent
Dilute NaOH added
Add nitric acid to remove any hydroxide ions
Silver nitrate test

Question 3

Test for an alcohol

Answer 3

Add K2Cr2O7 (acidified potassium dichromate)
Orange colour goes green

Question 4

Test for aldehyde

Answer 4

K2Cr2O7 / Tollens reagent / Fehlings solution
Orange to green / Silver mirror / brick red ppt

Question 5

Test for carboxylic acid

Answer 5

Add sodium hydrogen carbonate (NaHCO3)
Bubble gas produced through limewater
Limewater goes cloudy

Question 6

Describe how infrared spectra can be used to distinguish between A, B and C

Answer 6

Peak at ___ indicates ______
Peak at ___ indicates ______
Fingerprint region different
Compare to a known database

Question 7

Why do carbon dioxide, water vapour and methane all cause global warming

Answer 7

C=O, O-H and C-H bonds all absorb infrared radiation emitted by the earth, causing heat to be trapped in the atmosphere