Important colour changes

Important colour changes

Reaction	From	To
Alkenes and bromine water	orange	colourless
Alkanes and bromine water	orange	remains orange
Chlorine with damp litmus	blue	red thenwhite/bleached
Hydrogen chloride – dry with blue litmus	blue	remains blue
Hydrogen chloride with damp blue litmus/hydrogen chloride in water with blue litmus	blue	red
Hydrogen chloride in methylbenzene with dry litmus	blue	blue
Test for the presence of water – anhydrous copper sulphate	white	blue
Reaction of copper with concentrated nitric acid		blue solution and brown fumes
Reaction of copper (II) salts with sodium hydroxide (test for Cu2+)	blue solution and colourless solution	light blue precipitate
Reaction of iron(II) salts with sodium hydroxide – test for Fe2+	green solution	green precipitate
Reaction of iron(III) salts with sodium hydroxide – test for Fe3+	orange brown solution	red brown precipitate
Sodium chloride + nitric acid + silver nitrate – test for Cl-	colourless solution	white precipitate
Sodium bromide + nitric acid + silver nitrate – test for Br-	colourless solution	pale cream precipitate
Sodium iodide + nitric acid + silver nitrate – test for I-	colourless solution	yellow precipitate
Sulphate compounds and barium chloride	colourless solution	white precipitate
Heating copper carbonate	green solid	black solid
Zinc or magnesium in copper sulphate solution	grey metal in blue solution	colourless solution and black solid
Magnesium burning forming magnesium oxide	silvery shiny solid	white solid
Colours of groups 1 and 2 compounds	white solids	colourless if dissolved in water
Hydrochloric acid and ammonia - neutralization	two colourless gases	white solid
Chlorine water and sodium bromide solution	two colourless solutions	yellow solution
Chlorine water and sodium iodide solution	two colourless solutions	brown solution
Bromine water and sodium iodide solution	two colourless solutions	brown solution
Heating hydrated copper sulphate	blue solid	white solid