Purity of egg shell

Results

Mass of eggshell=27.55g

Mass of filter paper + egg-shell residue= 15.6g

Mass of filter paper without residue=2.06g

Calculations

1. Mass of residue= (mass of filter paper + residue)-(mass of dry filter paper)

=15.6-2.06

=13.14g

2. Mass of calcium carbonate= (Initial mass of eggshell)-(mass of residue)

=27.55-13.14

=14.41g

3. Percentage purity of egg shell=

=

=52.3%

Equations

Word equation

Calcium carbonate(s) + hydrochloric acid (aq) →Calcium chloride (aq) + carbon dioxide (g) + water (l)

Chemical equation

CaCO3(s) + 2HCl (aq) → CaCl2 (aq) + CO2 (g) + H2O (l)

Ionic equation

Ca2+(s) + CO32-(s) + 2H+ (aq) + 2Cl- (aq) → Ca2+ (aq) + 2Cl- (aq) + CO2 (g) + H2O (l)

CO32-(s) + 2H+ (aq) → CO2 (g) + H2O (l)

Precautions:

• Don’t forget to ground the eggshell into smaller pieces in order to increase the surface area as this speeds up the reaction.
• Do not tamper with the filter paper during the experiment as you may allow foreign bodies to enter
• Make sure that the filter paper is in good condition
• Make sure that the Electronic scale is correctly set up before recording any of the masses.

Limitations and difficulties:

• Due to its thinness, removing the inner lining from the eggshell was a difficult task, as well as time consuming.
• Lack of time to repeat the experiment due to time being wasted peeling off inner lining of egg shell
• Eggshell was very brittle hence a lot of it tended to blow away and break off.

Improvements:

• Experiment could be repeated several times in order to get a wider range of data
• Buying eggshells without the inner lining before hand would have saved a lot of time
• Make sure to close all windows so as wind does not blow away the eggshell.

Conclusion:

The percentage purity of the egg shell was 52.3% although results may vary due to the limitations, which does indeed leaves room for error.