chemical tests + gasses in the atmosphere Flashcards
how do you test for lithium?
place the nichrome wire with the solution into a non-luminous flame, if lithium is present it will burn red
how do you test for sodium?
place the nichrome wire with the solution into a non-luminous flame, if sodium is present it will burn yellow/orange
how do you test for potassium?
place the nichrome wire with the solution into a non-luminous flame, if potassium is present it will burn lilac
how do you test for calcium?
place the nichrome wire with the solution into a non-luminous flame, if calcium is present it will burn orange/red
how do you test for copper?
place the nichrome wire with the solution into a non-luminous flame, if copper is present it will burn blue/green
how do you test for cations
you add an alkali such as sodium hydroxide (NaOH) to the solution.
what is the result of testing for NH4?
ammonia gas produced
what is the result of testing for Cu ^2+?
blue precipitate of Cu(OH)2
what is the result of testing for Fe^2+
green precipitate of Fe(OH)2
what is the result of testing for Fe^3+
brown precipitate of Fe(OH)3
what is the chemical test for water?
you add anhydrous copper sulfate. which is a white powder.
if water is present in the chemical test for water, what happens?
the anhydrous copper sulfate becomes hydrated copper sulfate which are bright blue crystals
how do you test for hydrogen?
when a lit splint will burn with a squeaky pop
how do you test for oxygen?
a glowing splint relights
how do you test for carbon dioxide?
turns limewater milky
how do you test for ammonia?
turns damp red litmus paper blue
how do you test for chlorine?
turns damp blue litmus paper red before bleaching it white
how do you test for anions and why?
you test for halide ions using dilute nitric acid and silver nitrate. this is to remove carbonate / sulfate ions that would result in a false positive
how do you test for Cl- and what is the result?
you use silver nitrate and a white precipitate of AgCl is formed
how do you test for Br- and what is the result?
you use silver nitrate and a cream precipitate of AgBr is formed
how do you test for I- and what is the result?
you use silver nitrate and a yellow precipitate of AgI is formed
how do you test for Co3^2- and what is the result?
add hydrochloric acid and CO2 is produced
how do you test for SO4^-2
add barium chloride, a white precipitate of BaSO4 is produced
