Ong Jian HeOng Jian He STEVEN HIRAWANSTEVEN HIRAWAN

Tan YuehanTan Yuehan

Group Name: ^Atrix Group Name: ^Atrix Sec 3/2Sec 3/2

What is our aim for doing this project?What is our aim for doing this project?

For Fun?For Fun?Hmm… The answer is Hmm… The answer is here...here...

Our Aim for this investigative Our Aim for this investigative project is to deduce out which project is to deduce out which shells, the eggshell or the shells, the eggshell or the seashell, contains the most CaCOseashell, contains the most CaCO33..

What are the methods we What are the methods we have tried out?have tried out?

Compare the mass of Compare the mass of the COthe CO22 gas produced gas produced by the 2 shells when by the 2 shells when both are reacted with both are reacted with Acid.Acid.

Reverse TitrationReverse Titration

Are they successful?Are they successful?

Only the Reverse Titration method is successful

HELP!HELP!

Compare the masses of the COCompare the masses of the CO22 gas produced gas produced

by the 2 shells when reacted with Acid.by the 2 shells when reacted with Acid.

Apparatus:Apparatus:a) a) A rack of Test tubesA rack of Test tubesb) b) 2 stoppers2 stoppersc) c) 2X 10cm2X 10cm33 of HCl of HCld) d) Balloons Balloons e) e) 1 beam balance1 beam balancef) f) 1 pipette 1 pipette g) g) 1 pounder1 pounder

MethodMethodMethods:

- Collect Eggshells and seashells- Smash and Crisp them into small pieces- Collect the same amount of volume of the 2 shells. E.g 2g of Eggshells and seashells.- Put the powdered shells into 2 same set-up that shown below.

-Tie the balloon with the mouth of the delivery tube. Measure the volume of the balloon without any air spaces first.-Pour 6cm3 of the HCl into each set-up and push the stopper in to prevent and to transfer the CO2 gas into the balloon.-Untie the balloon cautiously to ensure no CO2 gas escape.-Measure the mass of the 2 CO2 gas produced.

No. OfExperimental

Tries

1 2 3 4

Volume ofAcid Used

(cm3)

6 6 6 6

Volume ofEgg Shells

used (g)

2 2 2 2

Volume of SeaShells Used

(g)

2 2 2 2

Mass of CO2

gas Produced[Egg Shells]

(g)

5.55 5.57 5.56 5.58

Mass of CO2

gas Produced[sea shells] (g)

4.60 4.60 4.60 4.60

- Mass of shells

- Volume of Acid

- Mass of CO2 gas collected

Yuehan is pouring 6cc of HCl to react the shells

Jian He is pouring the shells into the test tube

• There may be gas leak in the set-up, especially in the seashell reaction as it is very vibrant. More CO2 will escape.

• The reaction may not be ended even though you seen the balloon stops inflating.

• There may be some gas motioning about even you had seen the balloon inflates. If you remove the balloon, the gas will be gone

• The vapour may get into the balloon. Hence, causing wrong measurement.

From the above experiment, we can conclude that Egg shells contain more Calcium Carbonate as more Carbon Dioxide is been produced. If a certain shell produces more Carbon Dioxide gas than the other shell, it is concluded that the particular shell contains more Calcium Carbonate. Carbon Dioxide gas is produced when reacted with acid as specified in the acid general rules. The amount of Carbon Dioxide gas produced depends on the concentration of the shell.

2HCl + CaCO2HCl + CaCO33 ---> CaCl ---> CaCl22 + CO + CO22 + H + H22OO

Hmm… what is the second Hmm… what is the second method?method?

HELP!HELP!

- Burette - 1 pounder

- Pipette

- Burette Clip

- 2 Conical Flask

- 2 beakers

- Phenolphthalein

- 2M of HCl

- 2M of NaOH

- Beam Balance

Method:

- Pound the Shells into crisps

- Weigh the shells and collect the same amount. E.g. 0.5g of Eggshells and seashells. Put them into 2 separate beakers each.

- Add 0.05dm3 HCl into both beakers of shells.

- Use a pipette to abstract 0.025dm3 of reacted HCl solution

from each flask. Transfer the reacted 0.025dm3 of HCl

into 2 separate conical flasks.

- Add phenolphthalein into the conical flasks. (It should

be colorless with acid.)

- Pour 50cm3 of NaOH into the Burette.

- Tritrate till the solutions in the conical flasks turn pink

(pH 8).

TitrationResults

1 2 3 4

Volume ofHCl Used

[egg shells](cm3)

25 25 25 25

Volume ofNaOH used[egg shell]

(cm3)

21.0 21.2 21.1 21.0

Volume ofHCl used[sea shell]

(cm3)

25 25 25 25

Volume ofNaOH used[Sea Shell]

(cm3)

19.0 19.3 19.1 19.2

Mass of an egg: 11.96 / 2 = 5.98gMass of a seashell: 5gMass of Seashells and eggshells used: 0.5g

- Amount of shells used - Amount of HCl used (50cm3)

- Amount of CO2 gas produced- Amount of NaOH titrated

STEVEN HIRAWAN is having a hard time pounding the shells. Oh… poor him!

Seashells on the beam balance, waiting for transfer to test tube

•Excess HCl is used to collect the non reacted acid. If not, all acid will be dissolved with CaCO3.

• The amount of reacted HCl is different as the amount of CaCO3 in both shells are different. In this case, there will be different volume of not reacted HCl.

•NaOH is used to neutralize the non reacted acid. The lesser NaOH is used, more CaCO3 is presence in that particular shell. Similarly, more NaOH is used, lesser CaCO3 is presence.

Acid will neutralize with alkali to form Salt and Water. The amount of NaOH needed to neutralize with the acidic solution depends on the concentration of the CaCO3. If the concentration is greater than the other, it requires larger amount volume of NaOH to neutralize the solution.

HCl + NaOH ---> NaCl + HHCl + NaOH ---> NaCl + H22OO

- Raw eggshell has more CaCO3 content than boiled eggshell.- Shells in powdered form are more reactive in the acid than the non-powdered form shells.- Use as little acid as possible as the reaction is very strong- If heat is being introduced, the reaction will be greater and more CO2 gas will be produced.- Reverse Titration method is more accurate than Comparing of CO2 method. In titration method, its accuracy is due to the amount of NaOH to react with different concentration of reacted HCl with the 2 different shells.- Concluded that Comparing the mass of CO2 produced is an inaccurate method. - Seashell has more CaCO3 content than Eggshell.

We will like to take this opportunity to thank these people.

- Mr. Iskander for helping us out with the Titration method.

- Mr. Seow (HOD of Science) for guiding us throughout.

- Mr. Tok for giving us ideas too.