Chemical tests AS & A2

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Chemical Tests
Name: Test: Result:
Alkene (C=C) Add bromine water Bromine water turns orange to colourless
Carbonate (CO32-
) Add dilute nitric acid Limewater turns cloudy
Bubble gas through limewater
Sulphate (SO42-
) Add aqueous barium chloride White precipitate (BASO4)
will be formed
+SO42
Ba2+
BaSO4
Halides & haloalkanes Add aqueous silver nitrate +Cl- AgCl
Ag+
(Cl- , Br- , I- ) c if testing haloalkanes
Warm to 60o +Br- AgBr
Ag+
+I- AgI
Ag+
Add aqueous ammonia AgCl dissolves in dilute ammonia
AgBr dissolves in concentrated ammonia
AgI is insoluble in concentrated ammonia
Ammonium (NH4+
) Add aqueous NaOH
Warm NH3 gas is produced- can smell ammonia
Test with indicator paper NH3 will turn pH indicator paper blue
(alkali)
alcohol (CH2-OH)
1o Add acidified potassium dichromate Cr2O 2 3+
7 (orange) Cr (green)
Heat and distil An aldehyde is formed
Heat and reflux A carboxylic acid is formed
alcohol
2o Add acidified potassium dichromate Cr2O 2 3+
7 (orange) Cr (green)
(R1-CH(OH)-R
2)
Heat and distil A ketone is formed
alcohol
3o Add acidified potassium dichromate There is no colour change
(R1-C(OH)R2-R3) A tertiary alcohol cannot be further
oxidised
Carboxylic acid Add a metal carbonate Effervesce
(COOH) Bubble gas through limewater CO2 gas is given off
Limewater will turn cloudy
Ketones (R1-C=O-R2) Add 2,4-DNP
If no crystals form, add H2SO
4 Orange/yellow precipitate indicates ketone
or aldehyde
Aldehydes (R-C=O) Add 2,4-DNP
If no crystals form, add H2SO
4 Orange/yellow precipitate indicates
aldehyde or ketone

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Add Tollens' reagent
c for 10 minutes
Warm at 50o Silver mirror indicates aldehyde…read more

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