Why Do Soaps Not Form Lather in Hard Water? - Science


Why do soaps not form lather in hard water?



Soaps do not form lather in hard water because

Hard water contains calcium and magnesium salts. Soap molecules react with calcium and magnesium salts to form an insoluble precipitate called scum.

Concept: Soap
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2014-2015 (March) All India Set 1

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Differentiate between Toilet soap and Laundry soap.

Describe in brief the cleansing action of soap.

A student takes about 4 ml of distilled water in four test tubes marked P, Q, R and S. He then dissolves in each test tube an equal amount of one salt in one test tube, namely sodium sulphate in P, potassium sulphate in Q, calcium sulphate in R and magnesium sulphate in S. After that he adds an equal amount of soap solution in each test tube. On shaking each of these test tubes well, he observes a good amount of lather (foam) in the test tube marked

(A) P and Q

(B) Q and R

(C) P, Q and S

(D) P, R and S

Explain the formation of scum when hard water is treated with soap.

Distinguish between esterfication and saponification reaction with the help of the chemical equations for each. 

State one use of esterfication process.

 What change will you observe if you test soap solution with a litmus paper (red and blue)? Give reason for your observation.

Why have detergents replaced soap as a washing agent?


What is saponification? Write the chemical equation of the reaction involved in this process. Name all the substances which take part in this process and also those which are formed.

Give a scientific explanation.

Soap forms a precipitate in hard water. 

Differentiate between:
Detergents and Soaps.

Fill appropriate term in the blank:

Soap is a salt of _______ and sodium hydroxide.

Write an answer to the following question.

How will you check with the help of soap powder whether water is hard?

Write an answer to the following question.

What is meant by 'surface activity'?

Write an answer to the following question.

Name three chemicals responsible for the surface activity of various detergents.

What are the differences between Soap and synthetic detergent?

What are the similarities and differences between Bath soap and soap for washing clothes?

Explain Why Soap cannot be used in hard water.

Explain Why Synthetic detergents are superior to soap.

Explain Why Often coloured spots are formed on clothes during washing.

The saponification of a fat or oil is done using _____ solution for hot process.

Water, coconut oil, and _______ are necessary for soap preparation.

Match the following

1. Soap C6H5 OH
2. Cement CaSO4.2H2O
3. Fertilizers NaOH
4. Gypsum RCC
5. Phenol NPK

Arrange the following statements in correct sequence

  1. Pour that solution into an empty matchbox, soap can be obtained after drying.
  2. Take the necessary quantity of water in a jar.
  3. Then add coconut oil drop by drop and stir it well.
  4. Add concentrated sodium hydroxide in the jar and allow it to cool.
  5. Try this soap to wash your hand kerchief.
  6. Cover your work area with old newspaper.

What are the three main constituents of soap?

What are the two different types of molecules found in the soap?

TFM in soaps represents ______ content in soap.

The alkaline hydrolysis of fatty acids is termed as ______


Used to join components: Adhesives:: Clean the body ______.

______ to remove strong strains on the clothes.

______ are substances which can undergo chemical changes to produce certain materials.

______ molecules go and join with dirt and oil in the cloth.

The soap molecule has a

  1.  Write the formula and draw electron dot structure of carbon tetrachloride.
  2. What is saponification? Write the reaction involved in this process.

What are the similarities between Soap and synthetic detergent.


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