tests ch16 Flashcards
(6 cards)
how can you test if u have a primary secondary or tertiary alcohol
by adding 10 drops of the alcohol to 2cm3 of acidified potassium dichromate
warm the mixture gently in hot water bath
then watch it change colour
if it’s primary it will slower turn green same either way the secondary
and tertiary it will stay orange
how do you know if u have a secondary or primary alcohol
by adding my the excess alcohol to 2cm3 of acidified potassium dichromate solution in round bottom flask
set up the flash as part of the distillation apparatus
gently heat the flask. the alcohol will be oxidised and the product will be distilled off immediately and you can collect it
then you’ll find out if it’s an aldehyde or a ketone
what one way of finding out if its aldehyde or ketone
F
- use the feelings and benedict’s solution
- add 2cm3 of fehlings solution to test tube this will be blue solution
- add 5 drops of the aldehyde or ketone to the test tube
- put the test tube in a hot bath
if the solution turns brick red than it’s an aldehyde if not it’s a ketone
what’s another way of finding out if its ketones or aldehydes
T
by using tollens reagent
- put 2cm3 of 0.1 moldm -3 silver nitrate in a test tube
- add a few drops of dilute sodium hydroxide solution. a light brown ppt should form
- add drops of dilute ammonia solution until the brown ppt dissolves completely
- place the test tube in a hot water bath and add 10 drops of the aldehyde or ketone and wait for a few mins
- if it’s an aldehyde it will turn into a silver mirror
if it’s ketone then it won’t do anything
how to test for alkenes
add 2cm3 of the solution that you want to test in a testing tube
add 2cm3 of bromine water to the test tube
shake test tube
if it’s an alkene it will go from orange to colourless
how to test of carboxylic acids
carbonate test
- add 2cm3 of the solution that you want to test to a test tube
- add 1 small spatula of solid sodium carbonate
- if the solution begins to fizz, bubble the gas that it produces through lime water in a second test tube
- if it’s carboxylic then it will fizz and the carbon dioxide that’s produced will turn the limewater milky
