Physical Lab - Experimental Plan Essay Example | Topics and Well Written Essays - 500 words

Physical Lab - Experimental Plan - Essay Example The aim of this experiment is to apply the fluoride electrode method to a practical problem by measuring fluoride in tap water and to determine whether tea infusion from several types of tea increases the level of fluoride. 3. Serial dilution is done. This involves preparation of different less concentrated solutions from stock solution by dilution e.g. 10ml of 1000ppm stock solution is put in a volumetric flask and diluted with 100ml of distilled water to give 100ppm. A given range of standard solutions is obtained. 5. The ISE and reference electrode is then put into the least concentrated standard solution and allowed to adjust to room temperature and pressure and stirred gently after which electrode potential is measured. 7. Same volume of sample (tea) is measured and adjusted and the electrodes placed after which it is stirred and allowed to adjust to room conditions. Finally, electrode potential is measured. Calibration curves are then drawn. E=Eo+2.3RT/nFlog(Activity).Where, Eo is the Cell constant, RT/nF is the slope factor( shows the performance of electrode), n is ionic charge, R is the gas constant and T is the temperature in Kelvin. This process encounters a number of problems one of which is the release of other ions such as oxalate (www.chemistry.nmsu.edu)3. Other general problems encountered are related to erroneous values obtained due to sample contamination, junction clogging, and incorrect slope of the electrode (Wroblewsk, 2012)4. Such problems are generally rectified by using pure standards and using ISAB or decomplexing to adjust the conditions so as to avoid formation of other ions. Fluoride content of tea can then be compared with that of known solutions. Other methods such as one point calibration, incremental techniques, multiple sample addition and titrimetric procedures may be used. ISE is applied in Agriculture to determine level