Add water to the egg and stir before you pour it down the drain. 4. Wash the shell with deionized water and peel off the membranes from the inside of the shell. Dry your eggshell and put into a labeled beaker. 5. Wash your hands. 6. Dry the shell for about 10 minutes in the oven. 7. Grind the shell to a fine powder with a mortar and pestle. 8. Weigh between 0. 450 and 0. 550 grams of dried shell into each of the 3 labeled 250mL flasks. 9. Make sure to record the exact mass of the shell in each flask. 10. Add a few drops of ethanol to each flask. 1. Pour 40 mL of 1. 0M HCl into a beaker. 12. Put 10. 0 mL of the 1. 0M HCl to each 250mL flask containing the eggshells. Whirl the flasks to make sure all of the solids get wet. Be sure to spill any extra HCl into the sink with water. 13. On a hotplate, heat the solutions in the 250 mL flasks until they boil and then wait for them to cool. Be careful not to let them boil dry. Rinse flask with water. 14. Carefully, add 3-4 drops of phenolphthalein indicator to each flask. 15. Using a funnel, fill a buret partly with 0. 00 M sodium hydroxide, to rinse it. Empty the buret into the sink. Then, pour NaOH solution into the buret just above the top mark. Spill out some excess solution to remove all of the bubbles from the top. If there is not enough solution, refill some more into the buret. Read and record the initial volume to ± 0. 01 mL. 16. Add one sample to the first pink color. The color will fade once you are close to the endpoint. Add the excess NaOH little by little with a dropper pipet until the color is constant for at least 30 sec.
Read and record the final volume to ±0. 01 mL. Once the volume is added, it is the difference between the initial and final readings (to ± 0. 01 mL) 17. Repeat for the other samples. 18. Calculate the average value and the percent calcium carbonate in each sample. 19. Wash the egg residue out of the flask. CONCLUSION QUESTIONS 1)The amount of eggshell a student uses changes the outcome of the lab. It does matter because calcium may be unevenly distributed throughout the shell and there may be different concentrations around the eggshell.
If the student doesn’t add a certain amount of eggshells, the experiment will not have the correct outcome. 2)A student would be sure they added a sufficient amount of acid to completely react with all of the calcium carbonate by making the proper measurements. If there is not enough chemical activity like fizzing for example, the student can adjust the amount by adding more acid to make a greater reaction. 3)If the student failed to add sufficient HCl, it would affect their data in many ways.
Insufficient amounts oh HCl would not produce a complete reaction. The uneven amount would cause the reaction with CaCO3 to be unequal, so all the results would be directly affected. BIBLIOGRAPHY 1) "CHEM 1102. " Eggshell Experiment. N. p. , n. d. Web. 17 Mar. 2013. 2) "CHEM-212 Eggshell Lab. " CHEM-212 Eggshell Lab. N. p. , n. d. Web. 17 Mar. 2013. 3) "Stoichiometry. " Chem4Kids. com: Reactions:. Andrew Rader Studios, 1997-2012. Web. 19 Mar. 2013. 4) "To Determine the Percentage by Mass of Calcium Carbonate in Eggshells"
