Final answer:
Hard water that contains certain salts of calcium, magnesium, and other metals prevents shampoo from lathering properly. Water softeners can be used to remove these minerals and create soft water that allows shampoo to lather effectively.
Step-by-step explanation:
Water that contains certain salts of calcium, magnesium, and other metals that prevent shampoo from lathering is called hard water. Hard water is characterized by its high mineral content, specifically calcium and magnesium ions. These ions react with the surfactants in shampoo, reducing their ability to create lather.
When hard water is used with shampoo, the calcium and magnesium ions form insoluble compounds with the soap molecules, which prevents the shampoo from foaming and lathering properly. This can make it difficult to rinse out the shampoo and may leave a residue on the hair.
One way to overcome this issue is by using water softeners, which remove the calcium and magnesium ions from the water. Water softeners can be achieved through different methods, such as lime softening or ion-exchange resins, to create soft water that does not interfere with the lathering ability of shampoo.