Qualitative Analysis Lab Report

Potentiometric Titration of Sodium Carbonate
Otieno O. Victor
University of Detroit Mercy
Quantitative Analysis Lab CHM 3880
Fall 2011
Partner: Edwin Gay

Abstract
The PH at each point during the titration of sodium carbonate unknown sample was determined. An Unknown sample of Na2CO3 was titrated with a standard HCL solution. In addition to titration, the pH at each point of titration was measured using PH meter. The % of the unknown Na2CO3 was 25.83%
Introduction1
The purpose of this experiment was to determine the actual pH at each point during the titration of a sodium carbonate unknown with the use of pH meter.
An acid-base titration is a procedure which is used to determine the concentration of an acid or base. A measured volume of
The solution was then stirred with glass rode. The PH meter was standardized with 2 buffer solutions. The electrodes were washed and gently wiped with soft tissue. The electrodes were immersed in the solution and left immersed for the entire period of titration. The starting PH was recorded. A burette was filled with the standard HCl solution and starting volume noted. About 1.0mL of HCL was added to the solution and thoroughly stirred and PH recorded. The titrant addition was continued at about 1.0mL at a time. The PH and volume changes were recorded. At about 1.0-1.5mL of first equivalence, the titratnt was added in an increment of 0.2mL. The burette and the PH were recorded. However, me and my lab partner forgot to boil the solution when we were about 1.0 of second equivalence point. We continued with the titration with small increment of titrant until about 1.0-2.0mL beyond second equivalence point. Then, the electrodes were removed and rinsed thoroughly and then re-immersed in distilled
Table4: Volume of HCL and second derivative equivalence volume Vol NaOH (mL) | 2nd deriv Ve (mL) | Vol NaOH (mL) | 2nd deriv Ve (mL) | 1 | -0.02 | 23 | 3.5 | 2 | 0.07 | 23.225 | -0.266666667 | 3 | -0.05 | 23.5 | 0.666666667 | 4 | 0 | 23.775 | -0.333333333 | 5 | 0.04 | 24.075 | 0.714285714 | 6 | 0.01 | 7 | -0.05 | 8 | -0.01 | 9 | -0.08 | 9.825 | -0.112820513 | 10.275 | -2.066666667 | 10.55 | 1.666666667 | 10.875 | 0.047619048 | 11.2 | 0.444444444 | 11.5 | -5.777777778 | 11.775 | 3.133333333 | 12.025 | 0.733333333 | 12.3 | 0.888888889 | 12.6 | 1 | 13.1 | 0.181818182 | 13.975 | 0.040692641 | 15 | 0.11 | 16 | -0.05 | 17 | 0.02 | 18 | -0.05 | 18.875 | -2.36848E-15 | 19.5 | -0.16 | 20 | 0.16 | 20.5 | -0.16 | 21 | -0.52 | 21.425 | 0.257142857 | 21.725 | -3.266666667