CHEMISTRY INVESTIGATORY
PROJECT
Topic: Natural indicators f or
titration
INDEX
Certificate
Acknowledgement
Theory
Procedure
Observation
Conclusion
Bibliography
Acknowledgment
I extend my deep sense of gratitude to Ms. Sangeeta Bhowmik, whose constant
encouragement and supervision has made the present work possible it is she who
showed nuances of this project and motivated me to go for it. Her continuous
guidance and supervision at every stage of my project was a great boost for me.
Secondly, i am indebted to Mr. Rohit, who is in charge of the chemistry lab of
the school, for providing me with the equipment which were required to perform
this experiment pertaining to the project mentioned earlier and for his help at
each and every stage of this project.
Certificate
This is to certify that Board Roll No: _____________ of class 12th__ of
Father Agnel School, New Delhi has successfully completed his/her
Chemistry Investigatory project entitled “Natural indicators for titration” in
the school chemistry lab.
This work has been carried out under my supervision and guidance. It is
my pleasure that he/she has been able to prepare the project within the
stipulated time frame to my utmost satisfaction.
The progress of the project has been continuously reported and been in my
knowledge consistently. The approach towards the subject has been sincere
and scientific.
Mr Rohit Yadav Ms. Sangeeta Bhowmik CBSE Examiner
(Lab Assistant) (Chemistry Teacher)
Aim- To study the natural indicators for titration.
Theory-
Indicators are substances whose solutions change color due to change in
pH. These are called acid – base indicators. They are usually weak acids
or bases, but their conjugate base or acid forms have different colors due
to differences in their absorption’s spectra.
Types of Indicators
[1] NATURAL INDICATORS
A natural indicator is a natural substance that can be used to determine the pH
of another substance.
For example: turmeric, beetroot, onion, red cabbage etc.
[2] SYNTHETIC INDICATORS
A synthetic indicator is a man-made chemical substance used to determine pH.
For example: phenolphthalein, methyl orange, litmus etc.
VOLUMETRIC ANALYSIS: It involves determining the quantities
of a substance present in a given solution to react quantitively with a
solution of another substance of known concentration.
TITRATION: Titration is a process in which a fixed volume of
solution is taken in a conical flask, another solution of known
concentration is added to it with the help of a burette to bring about a
definite reaction to completion by reacting with the acid.
BASE – ACID TITRATION; Take a fixed volume of dil.HCL of
known concentration in a conical flask and add 2-3 drops of indicator.
Then add base from the burette till the pink color disappears, it is
called base-acid titration.
ACIDITY OF A BASE: It is the number of OH ions produced in
aqueous solution.
BASICITY OF AN ACID: It is the number of replaceable H+ ions
present in an acid.
What is pH?
PH is a measure of the hydrogen ion activity, typically in aqueous
solution.
Acidic solutions have pH < 7. pH values lower than 0 are possible.
Basic solutions have pH > 7. pH values greater than 14 are possible.
Beetroot as an indicator
Beetroot is a red glycosidic food dye obtained from its aglycone, obtained
by hydrolyzing the glucose molecule betanin.
The color of betanin depends on pH. It is bright bluish red becoming blue
violet as the pH increases. Once the pH reaches the alkaline levels betanin
degrades by hydrolysis resulting in a yellow brown color.
ONION AS AN INDICATOR
They have characteristic odor but when chopped and are kept in dil. NaOH
solution, they lose their odor. However, on keeping the chopped onions in a
dil. acidic solution, the characteristic smell of onion is not lost.
Materials Required-
Conical flask, burette, burette stand, pipette, white tile, water bath, tripod stand,
wire gauze, ethanol, beetroot, onion peel.
Procedure-
.PREPERATION OF BEETROOT INDICATOR
Step 1: Crush chopped beetroot nicely to form a thick paste
Step 2: Boil this paste with some water for about 5-7 minutes.
Step 3: Strain the indicator formed using a strainer. Keep it cool down
and come to room temperature so that it can be used for titration.
PREPERATION OF ONION PEEL INDICATOR
Step 1: Take an onion and remove its peel
Step 2: Take its peel and crush it as far as possible
Step 3: Add some water to the crushed onion peel and heat it in a water
bath keep stirring it regularly
Step 4: Now carefully add ethanol to the water bath heat more with
constant stirring. A pink color indicator is observed, strain it and keep it
at room temperature so that it cools down and can be used for titration.
Observations-
[1] Titration using phenolphthalein indicator
S. No. Volume of Acid Burette Reading Volume of Base
(HCL) Initial Final (NaOH)
[2] Titration using beetroot indicator
S. No. Volume of Acid Burette Reading Volume of Base
(HCL) Initial Final (NaOH)
[3] Titration using onion indicator
S. No. Volume of Acid Burette Reading Volume of Base
(HCL) Initial Final (NaOH)
3
CONCLUSION:
1)A color change was observed in strong acid strong base titration.
2)When the titration was conducted using beetroot as the indicator, the
color of the acid changed from colorless to light pink.
3)When the titration was conducted using onion peel as the indicator the
color of the acid changed from colorless to light yellow
4)
Precautions steps
1) Usually, an air bubble is present at the nozzle of the burette,
it must be removed before taking the initial reading.
2) There should not be any leakage from the burette during
titration.
3) Keep your eye level with the liquid surface while taking the
burette reading or while reading the pipette or measuring
flask etc.
4) Always read lower meniscus in case of colorless solution
and upper meniscus in case of colored solutions.
Sources of Error:
1) Misjudging the color of the indicator near the end point, this is
probably the most common one Sometimes color change is
delicate and slow and not everyone has the same sensitivity to
colors.
2) Transferring of two different solutions using a same pipette and
not rinsing pipette with distilled water in between.
Bibliography-
1. Saraswati chemistry laboratory manual.
2. SlideShare.net/sudeera22/beetroot-as-an-indicator.
3.www.chemicool.com
4.www.brainly.in
5.www.quora.com
