Chemical tests. Flashcards
What is the test for sulphates (SO4)?
HCl + BaCl2
Forms white precipitate (BaSO4)
What is the test for carbonates (CO3)?
Dilute HCl
Effervescence (CO2)
What is the test for OH- ions?
Turns damp red litmus paper blue.
What is the test for halide ions?
HNO3 + AgNO3
Nitric acid + Silver nitrate
Cl -> white ppt
Br -> cream ppt
l -> pale yellow ppt
How can you differentiate between AgX halides?
Cl -> dissolves in dilute ammonia (NH3)
Br -> dissolves in conc. ammonia (NH3)
l -> insoluble in conc ammonia (NH3)
What is the test for magnesium (Mg2+)?
NaOH
Forms white ppt (Mg(OH)2)
What is the test for calcium (Ca2+)
NaOH
Forms white ppt (Ca(OH)2)
How can you differentiate between Mg(OH)2 and Ca(OH)2?
Mg is insoluble in ammonia (NH3)
Ca is slightly soluble in ammonia (NH3)
What is the test for Sr and Ba?
H2SO4
Forms white ppt (SrSO4) (BaSO4)
How to differentiate between SrSO4 and BaSO4?
BaSO4 is less soluble
What is the test for ammonia (NH4+)?
NaOH (warm)
Damp red litmus paper turns blue.
What is the test for Co2+?
Ammonia (NH3)
Pink solution turns blue
What is the test for copper (Cu2+)?
NaOH - pale blue ppt
NH3 - blue solution
Na2CO3 - green-blue ppt
What is the test for copper (Fe2+)?
NaOH - green ppt
NH3 - green ppt
Na2CO3 - green ppt
What is the test for copper (Fe3+)?
NaOH - orange-brown ppt
NH3 - orange-brown ppt
Na2CO3 - orange-brown ppt and effervescence
What is the test for copper (Al2+)?
NaOH - white ppt
NH3 - white ppt
Na2CO3 - white ppt and effervescence
What colour flame does lithium produce?
Crimson
What colour flame does sodium produce?
Yellow
What colour flame does potassium produce?
Lilac
What colour flame does calcium produce?
Orange-red
What colour flame does copper produce?
Green
What is the test for alkenes?
Decolourises bromine water.
What is the test for primary and secondary alcohols?
Acidified potassium dichromate (K2Cr2O7)
Orange solution turns green
What is the test for tertiary alcohols?
Acidified potassium dichromate (K2Cr2O7)
Orange solution no change.
What is the test for alcohols?
Metallic Na
Produces effervescence (H2)
What is the test for aldehydes?
Fehling’s solution (warm) - Blue solution to a brick-red ppt.
Tollens’ reagent (warm) - Silver ppt formed (silver mirror).
What is the test for carboxylic acids?
Add a carbonate
CO2 released.
What is the test for oxygen gas?
Relights a glowing splint.
What is the test for hydrogen gas?
Lighted splint ignites with a squeaky pop.
What is the test for carbon dioxide gas?
Turns limewater cloudy (calcium carbonate ppt).
What is the test for chlorine gas?
Bleaches damp blue litmus paper.
