This document describes a biology investigatory project conducted by two students to test the pH of different soap samples. It includes an introduction, aim, theory on pH and how it is measured, materials used, procedures followed, observations recorded, and conclusions drawn. pH paper was used to test the pH of Dove, Pears, Medimix, Mysore Sandal, Lux, and Dettol soaps. The observations showed Dove was acidic while the others were basic, with pH values ranging from 5.3 to 10. The conclusion was that skin has an acidic pH of 5.5, so soap should have a slightly alkaline pH between 7.5 to 9.

1. KENDRIYA VIDYALAYA NO.- 2 BELAGAVI
CANTT
BIOLOGY INVESTIGATORY PROJECT
SUBMITTED BY:
ANISHA PRABHU & KHUSHI PANGI
CLASS: XII B

2. CERTIFICATE
This is to certify that this “BIOLOGY INVESTIGATORY PROJECT” on the
topic “pH TEST OF DIFFERENT SOAP SAMPLES” is successfully
completed by ANISHA PRABHU & KHUSHI PANGI of class XII B under the
guidance of MRS. G.K.VINAYAGAM MA’AM [PGT BIOLOGY] in particular
fulfillment of curriculum of CENTRAL BOARD OF SECONDARY
EDUCATION [CBSE] leading to the award of annual examination of the
year 2022-23.
TEACHER’S SIGN EXAMINER’S SIGN

3. AKNOWLEDGEMENT
I wish to express my gratitude to all the below mentioned guides who
have lead and motivated me to successfully complete my project.
I would like to thank my principal Mr. Arun Kumar Singh sir and the
school for providing me with the facilities required to complete my
project.
I am highly indebted to my biology teacher Mrs. G. K. Vinayagam ma’am,
for her valuable guidance which has sustained my efforts in all stages of
this project work.
My thanks and appreciation also goes to my fellow classmates in
developing the project and to the people who have willingly helped me
out with their abilities.

4. INDEX
Certificate
Acknowledgements
Aim
Theory
Materials Required
Procedure
Observations
Precautions
Conclusion
Bibliography

5. AIM
TO FIND THE pH OF DIFFERENT SOAP SAMPLES
Dove
Pears
Medimix
Mysore Sandal
Lux
Dettol

6. THEORY
pH is a measurement of the hydrogen ion concentration in an aqueous (water)
solution. Solutions with a high concentration of hydrogen ions have a low pH,
while solutions with a low concentrations of hydrogen ions have a high pH.
The pH of a solution is defined as the negative logarithm (base 10) of hydrogen
ion concentration

7. DIFFERENT WAYS TO TEST pH OF SOAP
Using Tongue Testing or Zap Testing to Check Soap Alkalinity
In this method of checking the soap pH is to touch a bar of soap to your tongue. If touching the bar of soap to your
tongue zaps similar to touching your tongue to a battery, it indicates a soap is lye heavy.
This method doesn't actually indicate the pH level of a soap, it simply indicates the presence of free alkali.
However, this is not a safe method to check pH of a soap.

8. Using Phenolphthalein Drops to Test Soap pH
Phenolphthalein drops are most commonly recommended for testing liquid soap and hot process soap
during the cook to identify whether the soap is "done" or if the soap needs to be neutralized.
The main issue with phenolphthalein drops is, when added to a solution, phenolphthalein changes from
clear to pink, depending on the pH of the solution. The initial color change from colorless to pale pink
happens at a pH of 8.2, and deepens to a dark fuchsia as the pH rises to 9.8. If used in a solution with a
higher pH, they remain bright deep pink. The correct pH value can not be determined. A soap with a pH of
10 will test exactly the same as a soap with a pH of 13. You will not get a proper and accurate pH value.

9. Using pH Strips to Test Soap pH
This is the most common method to check the pH of the soap. This method gives much more accurate pH
value than the previous methods if done correctly.
 pH Paper:
It is a strip of paper which is dipped in a solution of various indicators, and has been dried up. When it is
dipped in a given solution, it changes its colour. The shade of colour formed is compared to the chart
provided for this purpose, from which approximate pH can be found out.

10.  pH Scale:
The colour obtained on the pH paper, after dipping it in the given solution, is matched with the colour in the
pH scale and the corresponding pH value is noted.

11. MATERIALS REQUIRED
 Beaker
 Dropper
 pH paper
 pH scale
 Distilled water
 Soap samples
 White glazed tile

12. PROCEDURE
I. Take a very small piece of a soap sample in a beaker.
II. Add distilled water into the beaker and dissolve the sample.
III. Take one strip of pH paper with clean and dry hands and place it on a white
glazed tile.
IV. Using a dropper put 1 to 2 drops of soap solution on the pH paper.
V. Observe the colour obtained on the pH paper and compare it with the pH
scale.
VI. Note the pH value given on the obtained colour.
VII. Repeat the same procedure with other soap samples and note your
observations.

13. OBSERVATION
1 DOVE 5.3
2 PEARS 8.8
3 MEDIMIX 9
4 MYSORE SANDAL 10
5 LUX 9.4
6 DETTOL 9.8

14. RESULT
Acidic samples: Dove
Neutral samples: 0
Basic samples: Pears, Medimix, Mysore Sandal, Lux, Dettol

15. PRECAUTIONS
I. Wash the beaker thoroughly with distilled water each time before making a soap
solution.
II. Avoid using tap water for accurate readings.
III. Do not use pH paper directly on the soap bar. Always make soap solution then use
it.
IV. Use clean and dry hands to take pH paper strip.
V. Wash the dropper thoroughly after testing each sample.
VI. Clean and dry the glazed tile before use.
VII. All solutions should be freshly prepared.
VIII. The soap and water ratio in the solution should be same in all the samples in order
to get accurate readings.

16. CONCUSION
The neutral pH is 7. If the pH of skin is less than 7 it acidic. If it is
more than 7, it is alkaline. The pH of the skin will be 5.5. Skin
basically having acidic pH, that is the acid mantle to prevent all
the organisms from entering the skin. So the soap should be
slightly alkali. Anywhere between 7.5 till 9 should be used.

17. BIBLIOGRAPHY
 https://www.slideshare.net
https://www.modernsoapmaking.com
www.images.google.com

18. THANK YOU