Chemistry rainbow

UI = universal indicator; litmus: acid = red, neutral = purple, alkali = blue; methyl orange: acid = red, neutral = orange, alkali = yellow; phenolphthalein: acid = colourless, alkali = pink

red 4

litmus paper in acid

UI in HCl

methyl orange in acid

Li+ flame

brown 3

bromine liquid

Fe(OH)3 precipitate - reddish brown

NO2 gas

orange 6

Ca2+ flame

copper metal - rose brown

bromine water

bromine in organic solvent

UI in ethanoic acid (weak acid)

potassium dichromate (VI) before oxidation of alcohol

yellow 8

sulfur

methyl orange in alkali

flame in incomplete combustion

fuel oil

Na+ flame

silver bromide precipitate - cream

silver iodide precipitate - pale yellow

florine ions

green 5

UI in neutral solution

chlorine gas

Fe(OH)2 precipitate - blue/green

Cu2+ flame - blue/green

(potassium dichromate (VI) after oxidation of alcohol)

blue 6

litmus paper in alkali

UI in ammonia solution

Cu(OH)2 precipitate

hydrated copper sulfate

copper carbonate

(flame when sulfur burns)

purple 6

UI in sodium hydroxide

litmus solution in neutral

pink phenolphthalein in alkali

K+ flame

iodine vapour

iodine in organic solvent

black 3

bitumen

carbon

copper oxide

grey 2

iodine solid

zinc

white 6

barium sulfate precipitate

Cl bleaches blue litmus white

silver chloride precipitate

anhydrous copper sulfate

calcium carbonate

Mg+ flame

colourless 5

phenolphthalein in acid

limewater

gasoline

alkene in bromine water - orange → colourless

N2O4 gas