GRADE XII Chemistry Project

VELAMMAL BODHI CAMPUS
THANJAVUR
Chemistry Project Session:

2022-2023
Submitted by
Class – GRADE XIIth
Roll no. – ______
CONTENTS
1. Certificate
2. Declaration
3. Introduction
4. Theory
5. Activity
Aim
Apparatus required
Procedure
Result
Precautions
Conclusion
6. Bibliography
VELAMMAL BODHI CAMPUS
Certificate
This is to certify that ___________________________ student
of class XIIth (Sci.) has successfully prepared the report on the
Project under the guidance of Mr. __________________ (PGT
Chemistry). The report is the result of his efforts & endeavours.
The report is found worthy of acceptance as final Project report
for the subject Chemistry of class XIIth (sci)
Signature of Chemistry Teacher Signature of External Examiner
------------------------------------------- -----------------------------------------
Signature of Principal
-----------------------------
Declaration
I hereby declare that the project work
entitled
“_________________________________________
__________________________________________
__________________”, submitted to
Department of chemistry, VELAMMAL
BODHI CAMPUS THANJAVUR is
prepared by me.
NAME : ________________
CLASS : _________________
AIM : To study the digestion of Starch by
salivary amylase and effect of temperature and
pH on it. ”
Objective:
“To study the digestion of starch by salivary
amylase and effect of temperature and pH on
it” .
1. To study the digestion of starch by saliva.
2. To study the effect of temperature on the
digestion of starch by saliva.
3. To study the effect of pH on the salivary
digestion of starch.
Introduction
Every health book insists on the chewing of
food. The act of chewing stimulates the
excretion of saliva. Saliva mixes up with the
food and helps its digestion. That is, the enzyme
ptyalin or amylase present in human saliva
hydrolyzes the big molecules of food into many
molecules.
For example, starch into mono-saccnaricies
maltose and glucose; proteins into amino acids
and fats into fatty acids and glycerol.
Thus saliva not only helps in digestion of food
but also convert into energy generating
substances. Further, enzyme and their activity
are very sensitive to temperature and pH.
Even a slight variation in these two factors, can
disturb the action of enzymes. In other words,
digestion of food by salivary amylase is also
effected by temperature and pH and can be
verified experimentally.
For example, hydrolysis of starch can be verified
by testing it with iodine solution. Starch forms
blue coloured complex with iodine. If no starch
is present in a system it will not give blue colour
with iodine.
Apparatus Required
The requirements for experiment of chemistry
project report Are as follow:
1. Test tubes
2. Test tube stand
3. One dropper
4. Beaker
5. Stop watch
6. Starch
7. Iodine solution
8. Thermometer
9. Dilute HCl solution
10. Dilute NaOH solution
Experiment 1
Aim: To study the digestion of starch by saliva
Procedure for Chemistry Experiment 1 is:
1. Collection of Saliva:- Rinse mouth thoroughly with cold water
and ensure that it does not contain any food particles. Now
take about 250ml of lukewarm water in the mouth and keep for
about three minutes so that saliva mixes up well with it. Spit
this into a beaker. Filter, if there is any suspended impurity
clear filtrate is saliva solution and contains enzyme ptylin.
2. Preparation of starch solution:- Take about 0.5g of starch in
100ml beaker and add enough water to make a paste. Dilute
the paste by adding 50ml water and boil for about 5 minutes.
3. Digestion of starch:-
A. Take 5ml of the starch solution in a test tube. Add 2ml of
saliva solution into it. Mix the solution well by shaking the tube
carefully and start a step watch.
B. After one minute, take out two drops of the mixture solution
from the test tube with the help of dropper and transfer it into
another test tube containing about 1ml of 1% iodine solution.
Note the colour produced, if any.
C. Repeat this test after every one minute taking two drops of
the mixture solution and fresh 1% iodine solution continue until
the test shows no blue colour.
D. Record the time and blue colour intensity
OBSERVATION
Time Passed 1 Min 2 Min 3 Min 4Min

after Mixing
Colour Intensity Deep Blue Light Blue No Blue

Blue
Absence of blue colour on addition to iodine solution means

absence of starch in the mixture solution. That is whole of the
starch has got digested or hydrolysed.
Conclusion
Starch gets hydrolysed by salivary amylase
Experiment 2
Aim:-
To study the effect of temperature on the digestion of starch by
saliva.
Procedure for Chemistry Experiment 2 is:
1. Take three test tubes and label these 1,2, and 3.
2. Take 5ml of the starch solution, 2ml of the saliva solution and
5ml of water in each test tube. And shake the test tubes
carefully.
3. Place test tube number 1 in water at room temperature, test
tube number 2 in a beaker containing water at 50°C and test
tube number 3 in boiling water.
4. After 5 minutes, observe the colour change on mixing two
drops of the mixture of every tube with one ml of 1% iodine
solution. Note the intensity of blue coloured form
Conclusion
Temperature affects the digestion of starch by

saliva.
Experiment 3
Aim:- To study the effect of pH on the salivary digestion of
starch.
1. Take three test tubes and label these 1,2, and 3.

2. Add 5ml of the starch solution, 2ml of the saliva solution in
each test tube.
3. Now as 2ml of water in test tube number 1 2ml of Dilute HCl
in test tube number 2 and 2ml of Dilute NaOH solution in test
tube number 3 and shake carefully.
4. Keep the three test tubes in water at room temperature for
about 10 minutes.
5. Add 2 drops of the solution of each test tube with 1% iodine
solution and observe the colour change.
Observation
Colour produced (in
Test tube Solution taken test tube) with 1%
iodine solution
1 Starch + saliva + water No blue colour
2 Starch + saliva + dil. Blue colour

NaOH
3 Starch + saliva +dil. Blue colour

HCl
Conclusion
Hydrolysis of starch by the enzyme does not take place in the
acidic or alkaline medium.
Precaution
1. All apparatus should be clean and washed properly.
2. Add equal drops of iodine in all the samples while testing for
starch.
BIBLIOGRAPHY
 Comprehensive Practical Manual
 NCERT GRADE 12 Chemistry
 Wikipedia
 Analytical chemistry
 Google web page
 Chemistry journals

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VELAMMAL BODHI CAMPUS

Chemistry Project Session:

Signature of Chemistry Teacher Signature of External Examiner

Time Passed 1 Min 2 Min 3 Min 4Min

Colour Intensity Deep Blue Light Blue No Blue

Absence of blue colour on addition to iodine solution means

Temperature affects the digestion of starch by

1. Take three test tubes and label these 1,2, and 3.

1 Starch + saliva + water No blue colour

2 Starch + saliva + dil. Blue colour

3 Starch + saliva +dil. Blue colour

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