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In Villages, people often wash their clothes with well water. They have to rub a lot of soap before lather is formed. This is because well water is hard water. Thus, a lot of soap is wasted. However, if they use detergent powder in place of soap, lather is formed easily and wastage is less. Now, answer the following questions : (i) What values are expressed in the above paragraph? (ii) Why soap does not form lather with hard water? |
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Answer» Solution :(i) The values expressed in the above paragraph are that wherever WATER is hard, we should use detergent powder in place of SOAP for washing of clothes. (ii) Hard water contains `Ca^(2+)` ions and `Mg^(2+)`ions. Soaps are sodium salts of highers fatty acids, i.e., have the formula RCOONa. Soap first REACTS with `Ca^(2+)` and `Mg^(2+)` ion till they are removed from water `2 RCOONa + Ca^(2+) rarr (RCOO)_(2)Ca + 2 Na^(+)` `2 RCOONa + Mg^(2+) rarr (RCOO)_(2)Mg + 2 Na^(+)` Now, the water BECOMES soft and |
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