tests Flashcards
How do you test for an alkene?
Bromine water
What is observed when an alkene is added to bromine water?
The Bromine water changes from orange to colourless.
Why does an alkene decolourise bromine water?
It reacts by electrophilic addition
What does sodium carbonate test for?
Acids
What is observed when sodium carbonate is added to an acid?
Effervescence (CO2 gas is released)
What is observed when acidified potassium dichromate is added to a primary alcohol?
The dichromate is reduced changing from orange to green
What is observed when acidified potassium dichromate is added to a secondary alcohol?
The dichromate is reduced changing from orange to green
What is observed when acidified potassium dichromate is added to an aldehyde?
The dichromate is reduced changing from orange to green
What is observed when acidified potassium dichromate is added to a tertiary alcohol?
No change (tertiary alcohols can not be oxidised)
What is observed when acidified potassium dichromate is added to a ketone?
No change (ketones can not be oxidised by potassium dichromate)
What is observed when acidified potassium dichromate is added to a carboxylic acid?
No change (carboxylic acids can not be oxidised by potassium dichromate)
Tollen’s reagent is a test for which functional group?
Aldehyde
What is observed when Tollen’s reagent is added to an aldehyde?
A silver mirror forms
What happens to an aldehyde when it is tested using Tollen’s reagent?
the aldehyde is oxidised to a carboxylic acid
What is observed when Tollen’s reagent is added to a ketone?
No visible change
What reagent is used to test for ammounium ions?
Heat with NaOH
What is observed when ammounium (NH4+) ions are heated with NaOH
Gas released turns red litmus paper blue
What gas is released when ammonium ions are warmed with NaOH
ammonia gas (NH3)
What is Fehlings solution a test for?
Aldehydes
What is observed when an aldehyde reacts with Fehling’s solution?
Brick red precipitate
How do you test for a haloalkane
Add NaOH and warm to substitute the halide ion
Acidify with NHO3
Add AgNO3
Once a ppt is formed add dilute ammonia
Then add conc ammonia
What are the results for the haloalkane test
A white,cream, yellow ppt will form of AgCl,AgBr or AgI
On addition of ammonia, AgCl will dissolve
With conc ammonia- AgBr will dissolve but AgI ppt will remain
Test for hydrogen gas and result
Apply a lit splint
A squeaky pop
Test for CO2 gas
Bubbler through lime water- solution goes cloudy
