Explain why is hard water not form lather with soap?

Hard water contains high levels of minerals such as calcium and magnesium. When soap is added to hard water, these minerals react with the soap to form insoluble compounds known as soap scum. This prevents the soap from forming a lather and reduces its effectiveness in cleaning. The soap scum also leaves a residue on surfaces, making them appear dull and dirty. To overcome this issue, water softeners can be used to remove the minerals from the water, allowing the soap to lather properly.

Hard water is not able to form lather with soap because of the presence of dissolved minerals, primarily calcium and magnesium ions. These ions react with the soap molecules to form insoluble precipitates called "soap scum."

When soap is added to hard water, the calcium and magnesium ions in the water combine with the soap molecules to form calcium and magnesium soaps. These soaps are insoluble in water and form a scum on the surface of the water, preventing the formation of a lather.

The scum can also adhere to the skin, hair, and clothing, leaving a film that can feel rough and dry. It can also clog pipes and fixtures, reducing water flow and efficiency.

In contrast, soft water contains very few dissolved minerals, so it does not react with soap in the same way. When soap is added to soft water, it forms soluble sodium salts that do not precipitate out of solution. This allows the soap to form a lather and effectively cleanse surfaces.