Coloured ions
Many compounds have a colour. Different ions in aqueous solutions have different colour. By observing the colour of the aqueous solution, the ion species in the solution could be predicted preliminarily. The below are the colours of some ions that you need to memorise: Orange: Dichromate ion (Cr2O72-) Yellow: Chromate ion (CrO42-) Iron(III) ion (Fe3+) …