PAG 07 - Qualitative Analysis Of Organic Functional Groups Flashcards
(18 cards)
What reagent is used to test for presence of alkene
Bromine water
What is observed when bromine water is added to an alkene
Colour change
Orange to colourless
What’s observed when bromine water is added to a saturated Hydrocarbon
Solution remains orange
Briefly describe how to test for haloalkanes
Heat sample with NaOH under reflux to release halide ions
Add dilute nitric acid
Add silver nitrate and observe colour of ppt formed
What colour ppt forms when:
AgNO3 + Cl-
White
What colour ppt forms when:
AgNO3 + Br-
Cream
What colour ppt forms when:
AgNO3 + I-
Yellow
Describe solubilities of AgX ppt in dilute and conc ammonia
AgCl - soluble in dilute and conc ammonia
AgBr - soluble in conc ammonia
AgI - insoluble in ammonia
Briefly describe test for carboxylic acids
Add Na2CO3
Effervescence of CO2 produced
Test gas = bubble through lime water
CO2 = turn cloudy
What reagent used to test for alcohol
Acidified potassium dichromate solution
What’s observed when 1/2 alcohol is heated under reflux with acidified potassium dichromate
Orange to green
Observed when 3* alcohol heated under reflux with K2Cr2O7
No colour change remains orange
What 2 reagents can be used to distinguish between aldehyde/ketone
Fehling’s solution
Tollens’ reagent
Observed when fehlings solutio heated with aldehyde/ketone
Aldehyde = brick red ppt
Ketone = no ppt (remains deep blue colour)
Observed when heating tollens solution with aldehyde/ketone
Aldehyde = silver mirror forms on surface of test tube
Ketone - no change
What’s Brady’s reagent used to identify
Identify carbonyls
Yellow-orange ppt
Describe phenol test
Add Br2
Orange to colourless and white ppt form
When would water bath/electric heater be used instead of Bunsen burner to heat sample
When temp needs to be controlled more
When chemicals being heated are highly flammable
