The initial stages of the lab required the standardizations of ehylendiamineteraacetic acid by utilizing calcium carbonate solution containing CaCO3, water and 1:1 HCL acid as a titrant. Eriochrom Black T was added to the EDTA solution as an indicator in which turns from wine red to blue when an endpoint is reached. Three zinc lozenges in which were dissolved in a buffer solution maintaining a PH of 5.5, were then titrated with EDTA solution. The indicator Xylenol orange was added to the solution as it provided a definitive color change from pink to yellow when an endpoint was reached. When evaluating the results it was conclusively determined that the zinc lozenges within each trial contained 12.77 mg, 12.92 mg, and 13.06 mg of zinc. The percent average of zinc in each lozenge was calculated as 0.9246% Zn/Lozenge.
Data and Results
Table 1.1 Standardization of EDTA Solutions
Trial 1 Trial 2 Trial 3
Final Volume of EDTA in Burette (mL) 29.1 34.2 19.4
Initial Volume of EDTA in Burette (mL) 43.8 48.8 34.2
Total Amount of Titrant used (mL) 14.7 14.2 14.8
Amount of CaCO3 Reacted (g) 1.60x10^-2 1.60x10^-2 1.60x10^-2