chemical tests Flashcards
what is the test for CO3^2- and HCO3- ions
add aqueous acid
bubbles of CO2 gas will be observed
use delivery tube to pass CO2 through limewater
forms cloudy solution because CaCO3 precipitate forms
what is the test for NH4+ ions
add aqueous NaOH
warm mixture gently
ammonia gas produced
turns moist pH indicator paper blue
pungent smell given off
what is the test for SO4^2- ions
add HNO3 to remove carbonates
add aqueous barium chloride solution
white precipitate forms BASO4
what is the test for halides
add acidified AgNO3
add aqueous ammonia solution
Cl- white precipitate
Br- cream precipitate
I- yellow precipitate
add concentrated H2SO4
Cl- misty fumes of HCl
Br- brown vapour
I- purple vapour black solid
test for Mg2+
add NaOH
forms white suspension
test for Ca2+
add NaOH
forms white suspension
test for Sr2+ and Ba2+
add NaOH
both fully soluble
test for group 1 metal cation
add NaOH
all soluble
test for alkenes
decolorises bromine water
test for alcohol (OH group but not phenols)
add PCl5
misty fumes produced
add sodium
effervescence formed
test for carboxylic acid
turn litmus paper red
add a carbonate (HCO3-)
effervescence produced
test for aldehydes and ketones
add brandy’s reagent
orange precipitate formed
test to differentiate ketone and aldehyde
tollens solution
aldehyde - forms silver mirror
ketone - no change
fehling’s solution
aldehyde - blue -> brick red precipitate
ketone - stays blue
test to show alcohol -> aldehyde
add acidified potassium dichromate
orange -> green
(acidified with H2SO4)
test to show an esterification reaction
warm an alcohol and carboxylic with H2SO4
produces a characteristic smell
