Determination Of CaCO3 In The Egg Shell

1. CHEMISTRY
INVESTAGATORY
PROJECT
Submitted By : Vikash Prasad
1
XII – A
Roll No. :
Year : 2012 – 2013
Topic : Determination Of CaCO3 In An Egg Shell

2. School : Kendriya Vidyalaya No.2
CERTIFICATE
This is hereby to certify that the project “Determination
Of CaCO3 In An Egg Shell” is an original and genuine
investigation work carried out to investigate about the
subject matter and the related data collection and
investigation has been completed solely, sincerely and
satisfactorily by, VIKASH PRASAD of class XII – A as
per the requirement for the CBSE Board Examination for
the year 2012 – 13.
2
Roll No. :
Date :
Concerned Teacher Signature : Examiner Signature :

3. Principal Signature : School Stamp :
3

4. ACKNOWLEDGEMENT
I wish to express my deep gratitude and sincere
thanks to our chemistry teacher Mrs. Vijaylakshmi
for her invaluable guidance, constant
encouragement, constructive comments,
sympathetic attitude and immense motivation,
which has sustained my efforts at all stages of this
project work. Her valuable advice and suggestions
for the corrections, modifications and improvement
did enhance the perfection in performing my job
well.
I would like to express my gratitude for our
honorable principal Mrs. Shiny George for whole
hearted co-operation and guidance. I am also
thankful for her encouragement and for all the
facilities that she provided for this project work. I
sincerely appreciate this magnanimity by taking me
into her fold for which I shall remain indebted to
her.
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5. I take special pleasure in acknowledging our lab
assistant Mr. Ramesh G for her willingness in
providing us with necessary lab equipments and
constant support without which this effort would
have been worthless.
5
Vikash Prasad
Table of content
 Aim
 Introduction
 Theory
 Apparatus
 Chemicals Required
 Procedure

6. 6
 Calculations
 Result
 Precautions
 Bibliography
AIM
To measure the percent by mass of CaCO3 in an
eggshell

7. INTRODUCTION
During the 1960’s and 70’s the United States extensively
used a pesticide called DDT. Unfortunately, this pesticide
found its way into rivers and lakes and eventually into
wildlife birds of prey such as the Bald Eagle. Wildlife
biologists noticed that the eagle eggs were so thin that
they would break when the birds were hatching the eggs.
As a result, the Bald Eagle population plummeted in the
7

8. 1970’s to the point that there were estimated to be only
400 mating pairs of eagles in all of the lower 48 states.
This was thought to be due to the widespread use of DDT.
DDT was then banned for use and the Bald Eagle is no
longer on the endangered species list.
The strength of an egg can be determined by determining
the calcium carbonate content of the eggshell. The
percentage of calcium carbonate indicates that the
strength of the eggshell and the strength of the eggshell
show how serious the pesticide damaged to the eggshell.
This can be done by an acid/base titration. The following
reaction will be used:
HCl + CaCO3 → CaCl2 + H2O + CO2
THEORY
The major component of eggshells is calcium carbonate
(CaCO3). This analysis will be done volumetrically by using a
characteristic reaction of carbonate compounds, namely their
reaction with acids. Calcium carbonate (limestone) is very
insoluble in pure water but will readily dissolve in acid according
to the reaction
2HCl (aq) + CaCO3(s) → Ca2+ (aq) + CO2(g) + H2O + 2Cl-(aq)
8

9. This reaction cannot be used directly to titrate the
CaCO3 because it is very slow when the reaction is close to the
endpoint. Instead the determination is achieved by adding an
excess of acid to dissolve all of the CaCO3 and then titrating the
remaining H3O+ with NaOH solution to determine the amount of
acid which has not reacted with the calcium carbonate. The
difference between amount of the acid (HCl) initially added and
the amount left over after the reaction is equal to the amount used
by the CaCO3. The reaction used to determine the leftover acid is
HCl (aq) + NaOH (aq) → H2O + Na+ (aq) + Cl- (aq)
Apparatus
1. Pipette
2. Burette
3. Mortar and Pestle
4. Volumetric and Conical Flask
5. Glass Rod and Spatula
6. Beaker
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10. 10
Chemicals Required
1.Egg Shell
2.Ethanol
3.1.0 M HCL
4.0.1 M NaOH
5.Phenolphthalein
PROCEDURE
1. Boil an egg and allow it to cool. After some time wash the eggshell
with distilled water.
2. Obtain one half of an eggshell. Use a spatula to scrape away any
membrane that may be present inside the eggshell.
3. Use a mortar and pestle to grind the eggshell into a powder.

11. 4. Mass out 0.50 grams of the eggshell powder into a 125 mL flask and
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record the mass of the powder.
5. Add several drops of ethanol to the flask (this helps to the HCl to
dissolve the eggshell but is not part of the reaction).
6. Pipette 10.0 mL of 1.0 M HCl into the flask. Then add 2-3 drops of
phenolphthalein.
7. Fill the burette to above the 0.0 mL mark with 0.1 M NaOH. Open
the valve and allow the NaOH to drain into a small beaker until the
solution is at the 0.0 mL mark. The small amount of NaOH in the
beaker may be discarded.
8. Titrate the eggshell sample until the solution stays pink for 30
seconds. Read and record the final volume on the burette.
OBSERVATIONS
Trial 1 2 3
29.60 29.75 29.65 29.70
0.00 0.00 0.00 0.00
29.60 29.75 29.65 29.70
Final burette reading/cm
3
Initial burette reading/cm
3
Volume of NaOH used/cm
3

12. 12
CALCULATIONS
Molecular weight of CaCO3 = 100.1 g/mol
2HCl (aq) + CaCO3(s) → Ca2+ (aq) + CO2(g) + H2O + 2Cl-(aq)
HCl (aq) + NaOH (aq) → H2O (l) + Na+ (aq) + Cl- (aq)
1. Number of moles of NaOH used to react with HCl :
= VNaOH X MNaOH = 29.73/1000 L X 0.1 mol/L = 2.973 X 10-3 mol
2. Since number of moles of NaOH = Number of moles of HCl
= 2.973 X 10-3 mol
3. Initial number of moles of HCL = VolumeHCl X MolarityHCl
= 10/1000 L X 1 mol/L = 10-2 mol
4. Number of moles of HCl used to react with CaCO3 :
(10 X 10-3 – 2.97 X 10-3 ) mol = 7.07 X 10-3 mol
According to the equation two mole HCl required to react with one 1 mole
of CaCO3 :
5. Number of moles of CaCO3 reacted
= Moles of HCl reacted X (1mol of CaCO3 / 2 mol of HCl )
= 7.07 X 10-3 mol/2 = 3.535 X 10-3 mol
6. Weight of CaCO3 = 3.535 X 10-3 mol X 100.1 g/mol = 0.3535 g

13. in eggshell 70.07%
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7. The % of CaCO3 in eggshell :
= ( 0.3535 g/0.500 g ) * 100 %
= 70.07 %
Summary Of Calculations
No. of moles of NaOH used to react with HCl/ mol 2.97X 10
-3
No. of moles of HCl used to react with NaOH /mol 2.97X 10
-3
Initial moles of HCl / mol 1X10
-2
No. of moles of HCl used to react with CaCO
3
/mol
7.07 X10
-3
No. of mols of CaCO
3
reacted/ mol
3.535X10
-3
The weight of CaCO
3
/ g 0.3535
The % of CaCO
3
RESULT
The percent by mass of CaCO3 present in the eggshell is 70.07 % .
PRECAUTIONS
 Concentrated solutions should be handled with immense care.

14.  Hands should be washed thoroughly after performing each
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experiment.
 If possible, one should wear hand gloves to prevent from any
possible damage.
SOURCES OF ERRORS
 The eggshell powder did not dissolve completely.
 Variation in visual judgment at the end point.
 The eggshell was not fully dried up.
 Some droplets of solution may still adhere on the beaker and the
glass rod which lead to the reduction in number of moles of excess
HCl.
BIBILOGRAPHY
 Comprehensive Chemistry XII Lab Manual
 www.wikipedia.com
 www.google.com