Ong Jian He STEVEN HIRAWAN Tan Yuehan Group Name: ^Atrix Sec 3/2

What is our aim for doing this project? For Fun? Hmm… The answer is here... Our Aim for this investigative project is to deduce out which shells, the eggshell or the seashell, contains the most CaCO 3.

What are the methods we have tried out? Compare the mass of the CO 2 gas produced by the 2 shells when both are reacted with Acid. Reverse Titration Are they successful? Only the Reverse Titration method is successful

HELP!

Compare the masses of the CO 2 gas produced by the 2 shells when reacted with Acid. Apparatus: a) A rack of Test tubes b) 2 stoppers c) 2X 10cm 3 of HCl d) Balloons e) 1 beam balance f) 1 pipette g) 1 pounder

Method Methods: - 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 6cm 3 of the HCl into each set-up and push the stopper in to prevent and to transfer the CO 2 gas into the balloon. -Untie the balloon cautiously to ensure no CO 2 gas escape. -Measure the mass of the 2 CO 2 gas produced.

- Mass of shells - Volume of Acid - Mass of CO 2 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 CO 2 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 + CaCO 3 ---> CaCl 2 + CO 2 + H 2 O

Hmm… what is the second method?

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 0.05dm 3 HCl into both beakers of shells. - Use a pipette to abstract 0.025dm 3 of reacted HCl solution from each flask. Transfer the reacted 0.025dm 3 of HCl into 2 separate conical flasks. - Add phenolphthalein into the conical flasks. (It should be colorless with acid.) - Pour 50cm 3 of NaOH into the Burette. - Tritrate till the solutions in the conical flasks turn pink (pH 8).

- Amount of shells used - Amount of HCl used (50cm3) - Amount of CO 2 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 CaCO 3. The amount of reacted HCl is different as the amount of CaCO 3 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 CaCO 3 is presence in that particular shell. Similarly, more NaOH is used, lesser CaCO 3 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 CaCO 3. If the concentration is greater than the other, it requires larger amount volume of NaOH to neutralize the solution. HCl + NaOH ---> NaCl + H 2 O

- Raw eggshell has more CaCO 3 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 CO 2 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 CaCO 3 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.