Why is scum formed when hard water is treated with soap?

Answer 1

it can even occur with soft water the scum on the soap believe it or not is actually the scum from the cracks and crevises of your you body so shower more and no scum!

Liquid soap is a great alternative to bar soap, which can be messy - you'll always get residue in baths and showers - and less convenient to use than a liquid. Liquids are also less drying to the skin than bar soap, and there's no waste.

There are lots of liquid body and hand cleansers in pump-packs on the market, as well as refills, from plain, unscented Sorbolene-based liquids (good for allergy sufferers, generally cheaper, and very pleasant to use) to more expensive big-brand products.

Supermarkets and beauty shops sell little polyester netting-type shower 'sponges' you just pump a little liquid cleanser onto; they make the skin feel great, and just rinse clean.

Answer 2

The hard water contains insoluble carbonates and bicarbonates.

so hard water is when treated with water it gives insoluble carbonates (MgCO3,CaCO3) and bicarbonates (Mg(HCO3)2) and (Ca(HCO3)2) which form a scum like insoluble material.

Answer 3

Due to the presence of calcium ions and magnesium ions in hard water.