3.4.1: Organic Analysis

Question 1

Oxidising agent notation

Answer 1

[O]

Question 2

Test for primary for secondary alcohols

Answer 2

Add substance to 10cm3 of acidified potassium dichromate solution in a test tube
Warm mixture gently in a hot water bath

Question 3

Colour change to indicate primary and secondary alcohols

Answer 3

orange turns green

Question 4

Colour change for tertiary alcohols

Answer 4

no colour change

Question 5

Tests for primary alcohol
(after potassium dichromate test)
2

Answer 5

1= oxidise an alcohol under reflux and it tests positive for being a carboxylic acid its a primary alcohol
2=oxidise an alcohol under distillation conditions and it tests positive for being an aldehyde its a primary alcohol

Question 6

Test for secondary alcohol

after potassium dichromate test

Answer 6

oxidise an alcohol under reflux (or distillation) and its tests positive for being a ketone its a secondary alcohol

Question 7

Test for aldehyde or ketone

fehlings or benedicts solution

Answer 7

2 cm3 of (fehlings or benedicts solution) into a test tube
add 5 drops of aldehyde or ketone into a test tube
put the test tube in a hot water bath to warm it for a few mins
aldehyde = blue to brick red precipitate
ketone = solution will remain blue

Question 8

Tollens’ reagent

formation

Answer 8

2cm3 of 0.1 moldm3 silver nitrate solution in a test tube
add a few drops of dilute sodium hydroxide solution
a light brown precipitate should form
add a few drops of dilute ammonia solution until precipitate completely dissolves
= tollens’ reagent

Question 9

Test for aldehyde or ketone

tollens’ reagent

Answer 9

add tollens’ to substance in a test tube
and warm using a water bath
silver mirror effect = aldehyde
no change = ketone

Question 10

Test for carboxylic acids

Answer 10

add 2cm3 of the solution(being tested) into a test tube
add 1 small spatula of solid sodium carbonate
if the solution begins to fizz, bubble the gas produced through some limewater in a 2nd test tube
cloudy limewater = carboxylic acid
(NOTE: ANY ACID WILL BE POSITIVE,ONLY USE TEST FOR DISTINGUISHING BETWEEN ORGANIC COMPOUNDS WHEN YOU KNOW 1 IS A COOH*)

Question 11

Test for alkenes

Answer 11

add 2cm3 of the solution(being tested) into a test tube
add 2cm3 of bromine water to the test tube
shake the test tube
orange to colourless = alkene present