chemical analysis Flashcards
how do we test for hydrogen
using the squeaky pop test
how do you conduct the squeaky pop test
1) collect a sample pop gas in a test tube
2) put a lit splint into the test tube
3) if hydrogen is present there should be a squeaky pop sound
how do we test for oxygen
glowing splint relights test
how do we conduct the glowing splint test
1) collect a sample of gas in a test tube
2)place a glowing splint into the test tube
3) if oxygen is present the glowing splint relights
how do we test for water
using the copper sulphate test
boiling point test
how do we conduct the copper sulphate test
1) add anhydrous copper sulphate to the sample
2) if it changes colour from white to blue then oxygen is present
how do we use the boiling point test to see if water is present
1) measure its boiling point
2) the closer to 100c the pure the water is
what are cations
positive ions
what test do we use to determine what cation is present
flame tests that cause a non lumious bunsen flame to change colour
how to conduct a flame test
dip a piece of nichrome wire into HCL
dip the wire into a sample of solid or solution]
place the tip of the wire into a non luminous Bunsen flame
why do we dip nichrome wore into HCL before conducting a flame test
so that the wire is clean
what colour does li+ turn a non luminous Bunsen flame
red
what colour does NA+ turn a non luminous Bunsen flame
yellow
what colour does k+ turn a non luminous Bunsen flame
lilac
what colour does ca 2+ turn a non luminous Bunsen flame
orange/ red
what colour does cu2+ turn a non luminous Bunsen flame
blue / green
what test di we use to test for cu2+ fe2+ and fe3+
sodium hydroxide test
how do we conduct the sodium hydroxide test
1) dissolve the sample in water
2) add a few drops of NAOH
what colour does the metal cation cu2+ go in the sodium hydroxide test
blue
what colour does the metal cation Fe2+ go in the sodium hydroxide test
green
what colour does the metal cation fe3+ go in the sodium hydroxide test
brown
what is the precipitate formula for cu2+ in the NAOH test
cu(OH)2
what is the precipitate formula for Fe2+ in the NaOH test
Fe(OH)2
what is the precipitate formula for fe3+ in the NAOH test
fe(OH)3
how do we test for ammonium
using sodium hydroxide
how do we conduct an ammonium test
- dissolve the sample in water
- add some NaOH and warm it
- test the gas released with damp red litmus paper
- if ammonium ions are present the litmus paper will turn blue
what are anions
negative ions
how do we test for halides
using the silver nitrate test
how do we conduct the silver nitrate test
- dissolve the sample i water
- add nitric acid (HNO3)
- add silver nitrate solution (AGNO3)
what colour is the precipitate of the halide ion cl- in the silver nitrate test
white
what colour is the precipitate of the halide ion br- in the silver nitrate test
cream
what colour is the precipitate of the halide ion i- in the silver nitrate test
yellow
what is the precipitate formula of the halide ion cl- in the silver nitrate test
AgCl
what is the precipitate formula of the halide ion br- in the silver nitrate test
AGBR
what is the precipitate formula of the halide ion I- in the silver nitrate test
AgI
how do we test for carbonates
- add hydrochloric acid and look for effervescence
- if there is effervescence bubble the gas that is produced through lime water
- if carbonates are present in the example the gas produced will turn the limewater cloudy
how do we test for sulphates
- add HCL and look for effervescence
- if there is no effervescence add barium chloride (BACL2) solution
- if sulphate ions are present a white precipitate will form
