Potassium Iodide Lab

Abstract: The purpose of this lab was to use potentiometry to measure the concentration of a specific chemical species in a solution. This was conducted in 2 stages. The first stage involved making a solution of potassium iodide. The potassium iodide was then diluted to several different concentrations that were ran in potentiometer to find the mV of each solution which would then be used to find the PH of the solution. After analyzing a sample of each concentration an unknown solution was compared. Along with the the unknown tap water and deionized water were tested as standards.

Introduction:
A common method for determining the concentration of a solution is a titration. Titrations, however, are not the most efficient method for qualitative
Each solution was prepared to be the exact concentration. It is possible that in the first solution with the 0.1M that the wrong amount of Potassium Iodide was added. It was originally calcluated to be added to 50mL of water and not 100mLs. This calculation was redone in order to provide a larger amount of solution to work with. Any mistakes in concentration after this one are a result in accuracy and measuring. To make each solution correctly it was important to have exactly 10mL of solution and 90mL of water. If too much water is added it lowers the concentration and if too much solution is added it will raise the concentration even if only by tenths of a decimal. It appears to be an error in the measurement of the 10^-6 solution because it only differs by 7mv and each solution should increase or decrease by 0.059v or 59mv. It is theorized that this small change in measurement is because the electrode has a hard time detecting the mV of such a small concentration. Taking this into consideration the remainder of the points should be correct. They each increase by approximately 59mV as