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DETERMINATION OF CALCIUM CARBONATE IN EGGSHELLS
Member rating: No Rating | Words: | Submitted: Sat Mar 17 2007
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DETERMINATION OF CALCIUM CARBONATE IN EGGSHELLS BY ACID/BASE TITRATION OBJECTIVE To determine the mass percent of calcium carbonate (CaCO3) in an eggshell. INTRODUCTION During this lab, the percentage of CaCO3 in an eggshell is determined by reacting the eggshell with hydrochloric acid. The equation for this reaction is: 2HCl (aq) + CaCO3(s) ? Ca2+ (aq) + CO2(g) + H2O(l) + 2Cl- (aq) This reaction cannot be used directly to titrate the CaCO3. Instead, an excess of hydrochloric acid is added to dissolve the eggshell, and the remaining acid is titrated with NaOH solution to determine the amount of acid that did not react with the eggshell. The equation used to determine the amount of leftover acid is: HCl(aq) + NaOH(aq) ? H2O(l) + Na+(aq) + Cl- (aq) In order to help the hydrochloric acid dissolve the CaCO3, ethyl alcohol is added to the eggshell as a wetting agent. Wetting agents are chemicals that increase the spreading and...
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