Chemistry - inorganic analysis

flame test for cations method

the end of a nichrome wire is dipped into HCl then into the solid compound and placed in a roaring Bunsen flame

flame colour for lithium

red

flame colour for sodium

yellow

flame colour for potassium

lilac

flame colour for calcium

brick-red

flame colour for barium

apple green

flame colour for copper

blue green

what is a cation

positive ion

what are insoluble solids called

precipitates

sodium hydroxide test method

add sodium hydroxide solution to a solution of the substance to be tested

sodium hydroxide with ammonium

add sodium hydroxide solution and warm, no precipitate, pungent smell, when warmed NH3 gas released which turns damp red litmus paper blue

sodium hydroxide test calcium

white precipitate

sodium hydroxide test solution with magnesium

white precipitate

sodium hydroxide test iron ll

dark green, turns brown in air

sodium hydroxide test iron lll

rust-brown

sodium hydroxide test copper ll

pale blue

sodium hydroxide test ammonia

warm it and no precipitate formed but ammonia gas released

what is an anion

negative ion

carbonate/hydrocarbonate test and result

add any dilute acid to the unknown solid or solution

result - effervescence; gas turns clear colourless limewater cloudy due to formation of white precipitate. CO2 is produced

gas test for oxygen

glowing splint, splint relights

gas test for hydrogen

lit splint, squeaky pop

gas test for ammonia

damp red litmus paper turns blue or addition of HCl forms a white solid/ring

gas test for carbon dioxide

colourless limewater turns cloudy due to the formation of a white precipitate

gas test for chlorine

damp blue litmus paper, bleached white

gas test for iodine

starch solution, turns blue-black

gas test for water vapour

blue cobalt chloride paper turns pink or white anhydrous copper sulphate turns blue

gas test for hydrogen chloride

damp blue litmus paper turns red or addition of ammonia forms a white solid/ring

test for sulphate

add HCl then barium chloride makes a white precipitate of barium sulphate

test for chloride 

add dilute nitric acid then silver nitrate forms a white precipitate of silver chloride

test for bromide

add dilute nitric acid then silver nitrate forms a cream precipitate of silver chloride

test for iodide

add dilute nitric acid then silver nitrate forms a yellow precipitate of silver iodide

test for hydroxide 

add UI turns dark green, blue or violet 

ammonium ion and warm makes damp red litmus paper turn blue

test for hydrogen ion

add UI turns red, orange or yellow

add reactive metal which effervesces

add carbonate which effervesces

thermal decomposition of copper ll carbonate

heat in ignition tube from green to black

thermal decomposition of zinc carbonate

heat in ignition tube from white to yellow and back to white on cooling

which salts are soluble

sodium, potassium and ammonium salts, all nitrates, all chlorides except silver and lead (ll), all sulphates except barium, calcium and lead (ll)

which salts are insoluble

all carbonate except sodium, potassium and ammonium, all hydroxides except sodium, potassium and ammonium (not salts though)