In this experiment, we were showing how Acetic Acid and Hydrochloric Acid can be used to dissolve the shell of an egg. The calcium carbonate in the egg shell reacts with the acid to form a salt, water, and carbon dioxide. We started by diluting the stock 15M Acetic Acid and 12M Hydrochloric Acid to the molarities that we wanted. We used 250mL of four different concentrations of each acid (Table 1).
||Amount of stock acid used
Overall we used 108.75mL of stock Acetic Acid. Acetic Acid is $58.00 per Liter, meaning that we used about $6.30 of Acetic Acid. We used 37.49mL of Hydrochloric Acid. HCl is $41.00 per 500mL, so we used about $3.07 of HCl.
Above is the display set up. At this point all of the eggs still had their shells and were the same as they were in the package. In day 1, pictures below, all of the eggs formed bubbles around the shells. Up close you could hear the gas, CO2 trying to escape the jar. All of the eggs still had the shell and looked the same at this time.
After week one there was some significant changes in the eggs.
.1 M HCl: The shell on the egg did not do anything and when it was broken open it looked exactly like one that came out of the carton.
.2 M HCl: This egg cracked so we were unable to observe the results.
.5 M HCl: The shell dissolved completely, leaving only the membrane. The egg also denatured and cooked inside because of the acid.
1 M HCl: The egg completely denatured and was hard inside. The shell had dissolved and only the egg’s membrane was left
.435 M CH3COOH: The egg shell halfway dissolved. The egg was still white but it bounced.
.87 M CH3COOH: The shell off the egg dissolved completely and the egg and it was able to bounce.
1.74: The shell off this egg turned into a rubber material, but it did dissolve. This is why it is white in appearance. This egg also bounces slightly.
3.48 M CH3COOH: This egg denatured just like the .5 M and 1 M HCl.