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प्रश्न
Why does hard water not form lather with soap?
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उत्तर
With soap, hard water generates scum/precipitate. Soap containing sodium stearate \[\ce{(C117H35COONa)}\] interacts with hard water to form calcium and magnesium stearate (\[\ce{Ca/Mg}\] stearate). As a result, it is unsuitable for laundering. Because of the deposition of salts in the form of scale, it is also hazardous to boilers.
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संबंधित प्रश्न
Discuss the principle and method of softening of hard water by synthetic ion-exchange resins.
What do you understand by
Temporary hard water
What are the causes for
Permanent hardness
Name the substance which makes water permanently hard.
Explain with equation, what is noticed when permanent hard water is treated with
Slaked time
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?
Using given sample of temporary and permanent hard water, soft water, ordinary soap, detergent and washing soda how would you remove temporary hardness from water without 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.
Select the correct answer from the choice given in the options.
A substance which causes 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.
The pleasant taste of drinking water is due to the presence of a dissolved substance which includes air, CO2, and minerals.
Which water is hard?
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. Concentration of the solution is ______.
