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Question
What causes the temporary and permanent hardness of water?
Solution 1
Temporary hardness of water is due to the presence of soluble salts of magnesium and calcium in the form of hydrogen carbonates (MHCO3, where M = Mg, Ca) in water.
Permanent hardness of water is because of the presence of soluble salts of calcium and magnesium in the form of chlorides in water.
Solution 2
Temporary hardness of water is due to the presence of bicarbonates of calcium and magnesium in water i.e., Ca(HCO3)2 and Mg(HCO3) in water. Permanent hardness of water is due to the presence of soluble chlorides and sulphates of calcium and magnesium i.e., CaCl2, CaSO4, MgCl2 and MgS04.
RELATED QUESTIONS
Discuss the principle and method of softening of hard water by synthetic ion-exchange resins.
What do you understand by
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Permanent hard water
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Name the substance which makes water permanently hard.
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Slaked time
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Using given sample of temporary and permanent hard water, soft water, ordinary soap, detergent and washing soda how would you distinguish between temporary hard water and permanent hard water?
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Select the correct answer from the choice given in the options.
A substance which causes hardness in water _____.
Name or state the following:
A substance added to remove both temporary and permanent hardness in water.
Soap lathers well in hard water.
Match the following.
| Universal solvent | Water pollutant |
| Hard water | Kills germs |
| Boiling | Ozonisation |
| Sterilization | Water |
| Sewage | Stomach ailments |
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Hard water is not good for washing utensils.
What are the causes of temporary hardness and permanent hardness of water?
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The pleasant taste of drinking water is due to the presence of a dissolved substance which includes air, CO2, and minerals.
What is soft water?
Which water is hard?
Which water is soft?
Take samples of water from different sources (like a tube well, a lake, a pond, or a river) and pour equal quantities of each sample of water into different test tubes. Measure the height of water in each test tube with a scale. Add one or two drops of liquid soap to each test tube. Shake each test tube five times and observe the height of the lather in each sample. Record your observations in the table. Which water is soft? Which water is hard? Can you say why?
1000 g aqueous solution of CaCO3 contains 10 g of calcium carbonate. Hardness of the solution is ______.
