The determination of calcium carbonate present in the Eggshells.
Name: CH. Vyshnav
Date of experiment; 21/10/2013
The Major component of eggshells is calcium carbonate (CaCO3). This analysis will be done volumetrically by using a characteristic reaction of carbonate compounds, namely their reaction with acids. Calcium carbonate (limestone) is very insoluble in pure water but will readily dissolve in acid according to the reaction:
2HCl (aq) + CaCO3(s) Ca2+ (aq) + CO2(g) + H2O + 2Cl- (aq) |
This reaction cannot be used directly to titrate the CaCO3 because it is very slow when the reaction is close to completion (endpoint). Instead, the determination is achieved by adding an excess of acid to dissolve all of the CaCO3 and then titrating the remaining excess H3O+ with NaOH solution to determine the amount of acid that did not react with the calcium carbonate. The difference between amounts of the acid (HCl) initially added and the amount left over after the reaction is equal to the amount that is used by the CaCO3. From this, the amount of CaCO3 in the sample can be calculated.
The reaction used to determine the leftover acid is:
HCl (aq) + NaOH (aq) H2O + Na+ (aq) + Cl- (aq)
Aim: the main aim of this experiment is to find out the percentage of CaCO3 present in eggshells.
CHEMICALS REQUIRED ARE:-
Chemicals Required | Concentration Taken |
Egg shell (calcium carbonate) | - |
Hydrochloric Acid ( HCl ) | 1.0 mol dm-3 |
Ethanol ( C2H5OH) | Few drops |
Sodium Hydroxide ( NaOH ) | 0.100 mol dm-3 |
Apparatus Taken | Quantity Taken | Uncertainty |
Conical Flask (250 ml) | 3 | - |
Weighing Bottle | 3 | - |
China Dish | 1 | - |
Pestle | 1 | - |
Spatula | 1 | - |
Electronic balance | 1 | ± 0.001 |
Tripod stand | 1 | - |...