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| 1. |
of scum when hard water is treated with soap |
| Answer» When a\xa0soap\xa0is used in\xa0hard water, a solid substance we call\xa0scum\xa0forms. This is because charged calcium and magnesium particles (called ions ) present in the\xa0water\xa0react with\xa0soap\xa0to form an insoluble substance.\xa0Only when all the calcium ions have been precipitated out as scum will the\xa0water\xa0lather. Thus the volume of\xa0soap\xa0solution measures the amount of\xa0hardness. Permanently\xa0hard water\xa0contains calcium or magnesium salts other than the hydrogen carbonates. | |