Chemical tests

Test for CO2

Turns limewater milky (sparingly soluble Ca(OH)2 forms insoluble CaCO3)

Test for chlorine Cl2

Bleaches damp litmus paper (Cl2 reacts with water to form HCl and HClO)

Test for hydrogen

Pops with a lighted splint

Test for oxygen

Relights a glowing splint

Test for carbonate ions

Add dilute acid, effervescence as CO2 produced

Test for sulfate

Add dilute nitric acid then aqueous barium nitrate - gives white precipitate

Test for chloride ions

Add dilute nitric acid then aqueous silver nitrate - gives white precipitate

Dissolves in dilute ammonia to give colourless solution (of [Ag(NH3)2]+ )

Test for bromide ions

Add dilute nitric acid then aqueous silver nitrate - gives cream precipitate

Dissolves in concentrated ammonia but not dilute ammonia

Test for iodide ions

Add dilute nitric acid then aqueous silver nitrate - gives yellow precipitate Dissolves in either concentrated or dilute ammonia

Test for iron (II) ions

Add aqueous sodium hydroxide, gives green precipitate, insoluble in excess

Test for iron (III) ions

Add aqueous sodium hydroxide gives orange/brown precipitate, insoluble in excess

Test for copper ions

Add aqueous sodium hydroxide - gives blue precipitate, insoluble in excess

Or add ammonium gives blue precipitate which dissolves in excess to give a blue solution

Test for calcium ions

Add aqueous sodium hydroxide - gives white precipitate, insoluble in excess

Test for aluminium ions

Add aqueous sodium hydroxide - gives white precipitate which dissolves jn excess

Test for H+ (any acid)

Turns blue litmus red or makes sodium carbonate effervesce (CO2 gas)

Test for water

Turns white anhydrous copper (II) sulfate into blue hydrated copper (II) sulfate (colour change reversed when hydrated salts are heated)

Test for unsaturated hydrocarbons

Turns bromine water from orange to colourless

Test for aldehydes

Produces a silver mirror from a colourless solution of Tollen’s reagent/a red precipitate from blue coloured Fehling’s solution - needs heat

Test for carboxylic acids

Release bubbles of CO2 gas when shaken with sodium carbonate solution

Test for acid chloride

Gives misery fumes of HCl with water

Test for alcohol

Add acidified potassium dichromate - turns orange to green

Manganate ion change of colour

When reduced to Mn2+, goes from deep purple/pink to colourless

Solubility of nitrates?

All nitrates are soluble

Solubility of group 1 and ammonium ions

All soluble

Solubility of chlorides

All chlorides expect for Ag, Pb and Hg

Solubility of hydroxides

All insoluble (expect those of group 1, ammonium, barium and strontium)

Aluminium hydroxide is amphoteric and dissolved in excess hydroxide

Calcium hydroxide is ‘sparingly’ soluble and a solution is known as limewater

Solubility of metal carbonates

All metal carbonates (expect those of group 1 and ammonium) are insoluble

Insoluble back solid?

Might be carbon (graphite), iodine or MnO2

Insoluble yellow solid?

Might be Sulfur

Test for sulfate ion

Add nitric acid (removes carbonate so no other precipitate forms), add barium chloride - barium sulfate forms - white precipitate

Test for amines

Turns litmus paper blue (naturally basic)

Test for arene

Burn in air - produce smoky flame and soot