Studying the comparative cleaning capacity of a sample of soap in soft and hard water


Aim

To study the comparative cleaning capacity of a sample of soap in soft and hard water.

Apparatus and Chemicals

  • Three test tube (20 mL)
  • Dropper
  • Test tube stand
  • Three beakers (100 mL)
  • Three glass rods
  • A measuring cylinder (50 mL)
  • A measuring scale
  • Underground water
  • Hard water
  • Distilled water
  • Soap solution

Principle

Hardness of water is generally due to the presence of salts of calcium and magnesium (hydrogencarbontes, Chloride and sulphates) in water. These salts are soluble in water. When soap is added in hard water, it reacts with the salts to form a scum, which is insoluble and floats on top of the water surface. The scum is formed due to the formation of insoluble calcium or magnesium salts of the fatty acid used in the soap formation. The soap in solution then becomes ineffective.

As shown above the salts of calcium and magnesium show similar reaction. Therefore, the presence of calcium and magnesium salts in water precipitates the soap thereby reducing its cleansing power and foaming capacity.

Procedure

  • Take three 100 mL beakers and label them as A, B and C.
  • Take 20 mL of distilled water in beaker A. In beaker B take 20 ml of underground water. In beaker C take 20 ml of hard water.
  • Put 10 drops of soap solution in each beaker with a dropper and stir the content of each beaker with separate glass rods.
  • Place three test tube in test tube stand and label them as A, B and C.
  • Pour 3 ml of the above solution in the corresponding test tubes.
  • Take test tube A and shake it ten times by placing thumb on its mouth.
  • Foam or lather will be formed by shaking the test tube. Measure the length of the foam produced immediately with the help of a measuring scale
  • Similarly, repeat last two steps with the remaining two samples.

Observations and calculations

  • Volume of the distilled water, underground water or hard water = 20 ml
  • Drops of soap solution added to each beaker = 10 drops
  • Volume of solution taken in each test tube = 3 ml
  • Number of times each test tube is shaken = 10
S.No. Mixture
( water + soap)
Test tube reading
Initial length (cm)
Test tube reading
Final length (cm)
Length of the foam produced
(cm)
1.Distilled water
(soft water)
2.Well water or
underground water
3.Hard water

Results

  • Maximum length of foam is formed in soft water.
  • Scum is formed in hard water.
  • Soft water is most suitable for washing purpose.

Discussion

For cleansing purpose, the foam needs to be produced which depends on free availability of soap. In hard water it is trapped due to scum, this makes the hard water unsuitable for washing.

Precautions

  • Stir the mixture carefully so as to avoid spilling of soap solution.
  • Shake every tube for equal numbers of times and in similar manner.
  • Measure the length of the foam produced immediately after its production.

Class 10 Physics Practicals

Class 10 Chemistry Practicals

Class 10 Biology Practicals

Comments

  • zoritoler imol
    Reply

    I went over this web site and I think you have a lot of fantastic info , saved to fav (:.

    1
    0
  • Jaqueline
    Reply

    Hello, yeah this post is actually nice and I have learned lot of things from
    it regarding blogging. thanks.

    Here is my website: Twicsy

  • Carma
    Reply

    you’re in point of fact a excellent webmaster. The website loading pace is incredible.
    It sort of feels that you’re doing any distinctive trick. Also, The contents are masterwork.
    you’ve performed a great process on this subject!

    Feel free to surf to my webpage … Twicsy

    1
    0
  • gralion torile
    Reply

    I take pleasure in, lead to I discovered exactly what I was having a look for. You have ended my 4 day lengthy hunt! God Bless you man. Have a nice day. Bye

  • vorbelutr ioperbir
    Reply

    You have brought up a very excellent points, appreciate it for the post.

  • vorbelutr ioperbir
    Reply

    I’ve learn several just right stuff here. Certainly worth bookmarking for revisiting. I wonder how much effort you set to create this kind of wonderful informative site.

    3
    0
  • zoritoler imol
    Reply

    I¦ll right away take hold of your rss feed as I can’t find your email subscription hyperlink or newsletter service. Do you have any? Please allow me know so that I could subscribe. Thanks.

  • vorbelutr ioperbir
    Reply

    I feel that is one of the most important information for me. And i am satisfied reading your article. But wanna observation on few general things, The web site style is wonderful, the articles is truly nice : D. Just right activity, cheers

  • vorbelutr ioperbir
    Reply

    I’m not that much of a internet reader to be honest but your blogs really nice, keep it up! I’ll go ahead and bookmark your website to come back later on. All the best

The maximum upload file size: 100 MB. You can upload: image. Drop file here