When 50% potassium hydroxide is diluted to 4% with water - a white precipitate is formed.Can you tell me why and what the precipitate us?

This is something I have never observed in Nature, unless a magnesium salt or calcium salt is dissolved in the water, as in well water.

Did you observe this?

Yes, I can explain that to you. When a 50% solution of potassium hydroxide (KOH) is diluted with water, a white precipitate is formed. This white precipitate is called potassium hydroxide monohydrate or potassium hydroxide (KOH) hydrate.

To understand why this happens, we need to consider the solubility of potassium hydroxide in water. Potassium hydroxide is a strong base and is highly soluble in water. However, when it is diluted from a concentrated solution (50%) to a more dilute one (4%), the solubility of potassium hydroxide decreases significantly.

At 4% concentration, the water is not able to hold as much KOH as it could at a higher concentration. As a result, the excess KOH starts to exceed its solubility limit and precipitates out of the solution as a solid.

The formation of a white precipitate indicates that the concentration of KOH in the solution has exceeded its solubility, leading to the formation of solid particles. These solid particles are the potassium hydroxide monohydrate crystals.

It's worth mentioning that the formation of this white precipitate can also be influenced by factors such as temperature, pH, and agitation of the solution. Altering any of these factors may affect the solubility of potassium hydroxide and the formation of the precipitate.

To recap, when a 50% potassium hydroxide solution is diluted to 4% with water, a white precipitate called potassium hydroxide monohydrate forms. This occurs because the concentration of KOH exceeds its solubility limit at the lower concentration, causing it to separate out as solid particles.