chemistry project-2 keshav

8/10/2019 Chemistry Project-2 Keshav

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CHEMISTRY

INVESTIGATORY

PROJECT

Name :

Class :

Roll No:

Year : 2014-2015


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Certificate

This is to certify that Keshav Jain of

Class XII-G, in the academic year 2014-

2015, has completed the project

To determine the amount of casein

present in different samples of milk.

under my guidance and supervisionand to my complete satisfaction.

______

Signature


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Acknowledgement

I express my sincere gratitude to Mrs.

Madhu Mahajan and Mrs. Anita

Sharma (Chemistry teachers) for theirvaluable guidance, and for giving useful

suggestions and relevant ideas that

facilitated an easy and early

completion of this project.

I also express my deep gratitude to our

lab assistants, who were instrumental

in this regard by providing all thenecessary materials required in this

project.


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IndexContents

Certificate

Acknowledgement

Aim

Description

Requirements

Procedure

Observation

Inference

Bibliography


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Aim

To determine the amount of

casein present in differentmilk samples.


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Description

Casein is the main protein constituent of milk.

It constitutes about 80% of the total protein

in cows milk and about 3% of its weight.

Proteins precipitate when milk is moderately

acidified. Casein is sparingly soluble in water,

but dissolves completely in alkalis or strong

acids. It is a complete protein, meaning that itcontains all the essential amino acids, which

the body cannot manufacture on its own.

When dried, it is a white, amorphous powder

without any taste and odour. It is a mixedphosphoprotein and occurs in milk as a

calcium salt (calcium caseinate) in the form of

micelles. The micelles have a negative charge.


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When an acid is added to the milk, the

negative charge is neutralized.

Calcium caseinate + acetic acid casein (s)

+ calcium acetate (aq)


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Requirements

Apparatus and Chemicals

250 ml beakersFunnel

Glass rod

Chemical balances

Test tubes

Filtration flask

Bunsen burner

Different samples of milk

1% acetic acid solution

Saturated ammonium sulphate solution


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Procedure

Take 20cc of cows milk in a clean, dry

beaker and add 20 mL of saturated

ammonium sulphate solution with

constant stirring. Fat and casein will

precipitate out.

Filter the solution and transfer the

precipitate into another beaker.

Add 30 mL of water to the precipitate.

Only casein dissolves in water, forming a

milky solution and leaving all the fat

undissolved.

Heat the milky solution to about 40C andadd 1% acetic acid solution drop wise,

when casein gets precipitated.


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Filter the precipitate, wash with water

and let the precipitate dry.

Weigh the dry solid mass in a previously

weighed watch glass.

Repeat the experiment with other

samples of milk.


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Observation table

Volume of milk taken in each case = 20 ml.

Name of the milk Weight of casein % of casein

Cow milk 0.68 g 3.4

Buffalo milk 0.84 g 4.2

Goat milk 0.66 g 3.3

Sheep milk 1.10 g 5.5


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Inference

Different milk samples

contain differentpercentages of casein.


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Bibliography

NCERT Class 12 Chemistry

Comprehensive PracticalChemistry

www.sciencebuddies.org

www.wikipedia.org
http://www.wikipedia.org/http://www.wikipedia.org/http://www.wikipedia.org/

chemistry project-2 keshav

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