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Test for CationsCations are positively charged ions (atoms or groups of atoms that have more protons than electrons due to having lost one or more electrons). Cations are attracted to negatively charged electrodes... More in Solution using NaOH (aq)
| Test | Observation | Inference |
| Sample solution + NaOH(aq) – in drops – in excess + Heat | Pale/light blue is precipitate formed. Precipitate is insoluble in excess NaOH(aq) Precipitate turned black. | Cu2+ present CuO is formed |
| Sample solution + NaOH(aq) in drops – in excess | Dirty green gelatinous precipitate is formed. Precipitate is insoluble in excess NaOH(aq) | Fe2+ present |
| Sample solution + NaOH(aq)– in drops – in excess | Reddish brown gelatinous precipitate formed. Precipitate is insoluble in excess NaOH(aq) | Fe3+ present |
Test for Cations in Solution using NH3(aq)
| Test | Observation | Inference |
| Sample solution + NH3(aq) -in drops -in excess | Pale/light blue precipitate is formed. Precipitate soluble in excess NH3(aq) to form dark blue solution. | Cu2+ present |
| Sample solution + NH3(aq)- in drops – in excess | Dirty green gelatinous precipitate is formed. Precipitate is insoluble in excess NH3(aq). | Fe2+ present |
| Sample solution + NH3(aq) – in drops – in excess | Reddish brown gelatinous precipitate is formed. Precipitate is insoluble in excess NH3(aq) | Fe3+ present |
Confirmatory Test for Cu2+; Fe2+ and Fe3+
| Test | Observation | Inference |
| Sample solution + NH3(aq) in excess Sample solution + Potassium hexacyanoferrate (II) solution [K4Fe(CN)6)aq) | Deep blue solution is formed Brown precipitate is formed | Cu2+ confirmed Cu2+ confirmed |
| Sample solution + Potassium hexacyanoferrate (III) solution, (K3(CN)6)(aq) | Light blue precipitate formed is | Fe2+ confirmed |
| Sample solution + Potassium hexacyanoferrate (III) (K3(CN)6)(aq) | Deep blue precipitate is formed | Fe3+ confirmed |
| Sample solution + Potassium thiocyanate solution (KSCN)(aq) | Blood red solution is formed | Fe3+ confirmed |
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