Potassium alum, for example, is found in the minerals kalinite, alunite, and leucite, which can be treated with sulfuric acid to obtain crystals of the alum. Most alums have an astringent and acid taste. They are colourless, odourless, and exist as a white crystalline powder.
Just so, is aluminum sulfate acidic?
Aluminium sulfate is sometimes used to reduce the pH of garden soil, as it hydrolyzes to form the aluminium hydroxide precipitate and a dilute sulfuric acid solution. An example of what changing the pH level of soil can do to plants is visible when looking at Hydrangea macrophylla.
What is the pH value of alum?
Alum is most commonly delivered as a liquid concentration, having a solids level of 8.3% as Al2O3 or about 50% as hydrate. Alum solutions are acidic. For instance, a 1% solution has a pH of around 3. Ionic species present in alum solutions are highly dependent on the degree of reaction with hydroxyl ions.