Ise Determination of Fluoride Content in Various Substances

ISE Determination of Fluoride Content in Various Substances CHM 222 A 4 / 20 / 2007 IntroductionThe ion selective electrode apply was make up of a facile / silver chloride reference electrode and a glass electrode. The pH of the electrochemical cell is determined by monitoring the electrical potential discrepancy between the half-cells. The glass electrode is an ion selective electrode (ISE), which hardly responds to the hydronium ion concentration / activity in a solution under a boastful range of conditions.In this experiment, we are step the fluoride ion concentration, which means our electrode responds to fluoride ion concentrations. Procedure And Data amount Solutions Concentration (M) Potential (mV) 0. 9967 x 10-6 15. 0 0. 9967 x 10-5 1. 4 0. 9967 x 10-4 -42. 0. 9967 x 10-3 -101. 1 0. 9967 x 10-2 -160. 8 0. 9967 x 10-1 -219. 0 Unknown 6 was used for this lab group. It produced a potential battle of -196. 8 mV. This was then used in the equation derived from o ur trite solutions and found to stick out a F- = 0. 0618 M. Preparation of the toothpaste sample was through by a sonicator.Then, the electrical potential difference was measured again, just as in the standard solutions and unknowns. It was found to obtain a potential of -85. 6 mV. Inserted into the equation, F- = 3. 31 x 10-4 M. CalculationsSee attached sheets. ResultsToothpaste F- = 3. 31 x 10-4 M Unknown 6 F- = 0. 0618 M Label Value in Toothpaste 0. 15% w/v cypher Value in Toothpaste 0. 8 mg / g 0. 8 mg/g converted to w/v (g/ ascorbic acid mL) is approximately 0. 1144% w/v. In equality with the label, the calculated error is found to be about -24%.A potential address of error could be found in the method of dissolving the toothpaste. There were a lot of bubbles formed, thus allowing for greater adventure of misreported volumes of solution. Also, the pH / V meter had fuss settling on values during the standard measurements, which would alter the regression line. The ISAB se emed to work fail with stronger concentrations of F-, as the regression line add up better toward the latter part of the plot. However, the pH region seemed to be less in-chief(postnominal) than the F- concentration.