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प्रश्न
Give a scientific explanation.
Soap forms a precipitate in hard water.
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उत्तर
When soap is mixed with hard water calcium and magnesium salts of fatty acids are formed. These being water insoluble they form a precipitate and that is why lather is not formed.
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संबंधित प्रश्न
Why do soaps not form lather in hard water?
List two problems that arise due to the use of detergents instead of soaps.
What change will you observe if you test soap with litmus paper (red and blue)?
A student took four test tubes P, Q, R and S and filled about 8 mL of distilled water in each. After that he dissolved an equal amount of Na2SO4 in P, K2SO4 in Q, CaSO4 in R and MgSO4 in S. On adding an equal amount of soap solution and shaking each test tube well, a good amount of lather will be obtained in the test tubes:
(a) P and Q
(b) P and R
(c) P, Q and S
(d) Q, R and S
Distinguish between esterfication and saponification reaction with the help of the chemical equations for each.
While studying the saponification reaction, what do you observe when you mix an equal amount of colourless vegetable oil and 20% aqueous solution of NaOH in a beaker?
(A) The colour of the mixture has become dark brown
(B) A brisk effervescence is taking place in the beaker
(C) The outer surface of the beaker has become hot
(D) The outer surface of the beaker has become cold
What change will you observe if you test soap solution with a litmus paper (red and blue)? Give reason for your observation.
State one advantage of soaps over detergent.
The soap molecule has a ______.
In a soap micelle, the soap molecules are arranged radially with:
(a) ionic ends directed towards the centre and hydrocarbon ends directed outwards
(b) hydrocarbon ends directed towards the centre and ionic ends directed outwards
(c) both ionic ends and hydrocarbon ends directed toward the centre
(d) both hydrocarbon ends and ionic ends directed outwards
Give the reason of formation of scum when soaps are used with hard water.
What are detergents chemically? List two merits and two demerits of using detergents for cleansing. State the reason for the suitability of detergents for washing, event in the case of water having calcium and magnesium ions.
Explain the action of soap in removing an oily spot from a piece of cloth.
The saponification of a fat or oil is done using _____ solution for hot process.
Water, coconut oil, and _______ are necessary for soap preparation.
What are the two different types of molecules found in the soap?
How does soap clean clothes?
______ to remove strong strains on the clothes.
- Write the formula and draw electron dot structure of carbon tetrachloride.
- What is saponification? Write the reaction involved in this process.
Why do soaps not work effectively in hard water?
