Calcium Carbonate and Eggshell

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Eggshell Lab

Name: _______________________________________________Date: _____________

Purpose: To determine whether there is a difference in the amount of calcium carbonate in brown versus white chicken eggs.

Background: Calcium carbonate (CaCO3) is a component of seashells and eggshells that gives them their strength and hardness. Because calcium carbonate is a base, it will react with acids to form a salt and water. The complete reaction of calcium carbonate with hydrochloric acid is: CaCO3 (s) + HCl (aq) ( CaCl2 (aq) + CO2 (g) + H2O (l)

The portion of the shell that is not calcium carbonate does not react with acid and remains as a solid. In this experiment you will perform the above reaction with both white and brown eggshells to determine if there is a difference in their composition.

Materials: Brown and white eggshells, 3M HCl, 250ml beaker, 100ml beaker, glass stir rod, graduated cylinder, funnel, filter paper, ring stand, balance

Procedure:

1. Obtain a sample of brown or white eggshell and record its mass. 2. Place the eggshell in a 250ml beaker and add 15ml of HCl. 3. Stir until all bubbling stops.
4. Obtain a piece of filter paper, white your initials on the edge with pencil, then record the mass of the paper. 5. Place the filter paper in the funnel, in the ring stand, and place the 100ml beaker below the funnel. 6. Filter your HCl-eggshell solution through the filter paper, capturing any unreacted eggshell in the paper. 7. Rinse the unreacted eggshell with water a few times, and then place the wet filter paper in the hood to dry overnight. 8. Repeat steps 1-7 with the other color of eggshell.

9. The next day, determine the mass of your dried filter paper and unreacted eggshell.

Data:

White Eggshell
Mass of eggshell: _________
Mass of filter paper: _________
Mass of filter paper +
unreacted eggshell: __________
Brown Eggshell
Mass of eggshell: _________
Mass of filter paper:...
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