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Question
What are the causes for
Permanent hardness
Solution
The presence of sulphates and chlorides of magnesium and calcium makes water permanently hard.
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RELATED QUESTIONS
Discuss the principle and method of softening of hard water by synthetic ion-exchange resins.
What are the causes for:
Temporary hardness
Name the substance which makes water temporarily hard
Name the substance which makes water permanently hard.
Explain with equation, what is noticed when permanent hard water is treated with
Slaked time
How will you distinguish between temporary hard water and permanent hard water?
Using given sample of temporary and permanent hard water, soft water, ordinary soap, detergent and washing soda how would you remove temporary hardness and permanent hardness from water using a chemical compound?
Both temporary & permanent hardness in water can be removed by addition of washing soda. Give balanced equations for the same.
State what are synthetic detergents. Explain experimentally how you will determine the advantage of synthetic detergents over soap using a sample of hard water.
Name or state the following:
A substance added to remove both temporary and permanent hardness in water.
Match the following.
| Universal solvent | Water pollutant |
| Hard water | Kills germs |
| Boiling | Ozonisation |
| Sterilization | Water |
| Sewage | Stomach ailments |
Give a reason for the following.
Hard water is not good for washing utensils.
What is soft water?
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?
