ii. TITRATION USING THE PH ELECTRODEThe primary data element collected from the titration using the pH electrode was the graph below from Figure1. Multiple steps performed in the traditional titration overlap with this exercise. However, it is important to acknowledge that a significant amount of human error was reduce in these measurements, due to the digital pH readings collected with the sensor and Vernier LabQuest device.05101520253035024681012pH Electrode Accurate TitrationNaOH (mL)1st Derivative pH LevelFigure 1.Graph of the best accurate titration using pH electrode collected in this experimentwhich was the data from trial 3.5Estimate of equivalence point at approx. 8.56 pH and 22.30mL of NaOH.
The graphical output of the Vernier LabQuest device was then exported into Logger Pro software in order to be processed and get the first derivative of the data shown in the orange color in Figure 1. The graph supports our initial accepted value of 8.5 pH at the equivalence point of the solution with an actual 8.56 pH which allowed us to determine the volume of NaOH at 22.30mL. Furthermore, Table 3 reflects the data recorded from each titration performed using the pH electrode.Trials1st derivative peak valuepH at the equivalence pointVolume of NaOH determined Accurate Titration 12.338.2823.4 mLAccurate Titration 23.068.6823.1 mLAccurate Titration 32.358.5622.3 mLTable 3. Summarizes the values obtained from each of the titrations performed, including the values for first derivative peak, pH at the end point, and volume of NaOH.Finally, calculations were made to determine the mean for the molarity of the citric acid as well as the standard deviation. These values are recorded in Table 4, and detailed calculations are present in the notebook. TitrationCalculated NaOHmoles (Using 0.0476M)Calculated moles of citric acid (Using moles of NaOH + balance equation)Molarity of citric acid using 20mL (mol/L)XmSxTitration 10.00111 moles3.713*10^-4 moles0.01860.0185M1.212*10^-4Titration 20.00109 moles3.665*10^-4 moles0.0183Titration 30.00111 moles3.697*10^-4 moles0.0185Table 4. Summary of final calculations from thetitration using the ph electrode.REFERENCESNovak, Michael. “Chapter 7 The Quantitative Determination of an Acid in Carbonated Beverages.” CHM 144 General Chemistry Laboratory Manual, by Yasmin Jessa, McMillan Learning, 2017.6