A few drops of dilute sodium hydroxide solution react to form a white precipitate with aluminium ions, calcium ions and magnesium ions. However, if excess sodium hydroxide solution is added ...

Then add 3-4 drops of 6M HCl and stir until the mixture becomes red. Add 4-6 sodium hydroxide pellets. As they dissolve at the bottom, the solution surrounding them will become dark blue. Gently stir ...