Question

Soap works in which of the following?
A.Soft water
B.Hard water
C.Both soft and hard water
D.None of these

Answer 1

Hint: Soap is a fatty acid salt that is used in a wide range of washing and lubricating goods. Soaps are surfactants that are commonly used in the home for washing, bathing, and other sorts of housekeeping. Soaps are utilised as thickeners, components of certain lubricants, and catalyst precursors in industrial settings.

Complete answer: The amount of dissolved calcium and magnesium as minerals in hard water determines its classification.
Soaps are fatty acid salts that are sodium or potassium based. Soaps react with the minerals in water to produce lather, which varies depending on the type of the water.
Water is divided into two types: soft water and hard water. Magnesium and calcium salts, as well as bicarbonates, sulphates, and chlorides, are found in hard water. There may also be ferrous ions present, which are oxidised to ferric form and appear as a reddish-brown stain on washed materials.
Other salts, such as sulphates and chloride, create permanent hardness of water, whereas calcium carbonate produces transient hardness.
The magnesium or calcium ions in hard water replace the sodium or potassium ions in soap molecules (which are made up of fatty acids) and cause a process that results in the formation of scum, an insoluble gelatinous curd-like material. In the case of hard water, this reaction hinders the production of lather with soap. So, water that easily lathers with soap is referred to as soft water rather than hard water. Soaps and detergents' cleaning activity is determined by their structures.
Hence option A is correct.

Note:
Soaps and detergents' cleaning activity is determined by their structures. They have the capacity to reduce water's surface tension, emulsify oil or grease, and keep it suspended in water. Detergent has a greater cleaning function than soap. Soaps have carboxylates, whereas detergents have polar sulfonates, which are more soluble in hard water and produce more lather than soaps.