tests for... Flashcards
How to test for sulphate ions?
dilute HCl
Barium ions
Ba 2+ (aq) + SO4 2-(aq) -> BaSO4
white precipitates form
How to test for carbonates?
Calcium hydroxide Ca(OH)2 aka limewater
reacts and form CaCO3
white precipitate
Why is HCl added before sulfate test?
To remove any carbonate ions to create false positive results
How to test for ammonium? NH4+
add sodium hydroxide to form ammonia gas and water, that turns red litmus paper blue
NH4+ + OH- -> NH3 + H2O
How to test for water
anhydrous copper(II) sulfate
white to blue
what state is smoke?
solid!!!!!!!!!!!!
what state are fumes?
gas!!
Why is HCl used in flame tests?
solid salt is converted into more volatile metal chlorides
Why is HCl used in tests for sulfates?
Remove carbonate ions
What is calcium chloride used for?
Drying agent, soaks up water
Anhydrous
What colour is NO2?
brown gas
What colour is O2?
colourless
What colour is NO3?
colourless
Why when testing for ammonia we need to use DAMP litmus?
So gas dissolves in it
What does starch react with?
IodiNe
I2 !!!
What are the colours of cyclohexane with halogens?
Non polar so halogens can better dissolve in cyclohexane
Chlorine pale yellow green
Bromine formed in top layer is ORANGE
Iodine top later is PURPLE
What colours are the halogens?
F2 - pale yellow
Cl2 - pale Green
Br2 - orange
I2 - brown
