To precipitate Al(OH)3 from potassium aluminate in KOH, you will need to add a strong acid, such as hydrochloric acid, to the solution until the pH reaches around 5. This will cause the Al(OH)3 to precipitate out of the solution.
KOH is used as a base in this process to neutralize any acid that may be present in the solution. This ensures that the pH of the solution remains in the optimal range for the precipitation of Al(OH)3.
Yes, you can use other strong bases such as sodium hydroxide or ammonium hydroxide. However, the amount used may vary and may affect the final pH of the solution.
You can test for the presence of Al(OH)3 by adding a few drops of a strong acid to the solution. If the solution turns cloudy or the pH decreases, then the Al(OH)3 has fully precipitated.
The precipitate can be separated from the solution by filtration. It can then be washed with water to remove any impurities and dried for further use or analysis.