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b.Use a utility clamp to attach the reservoir to the ring stand.c.Fill the reagent reservoir with slightly more than 60 mL of the MnO4–solution.d.Place the 250 mL beaker, which contains the rinse MnO4–solution, beneath the tip of the reservoir.e.Drain a small amount of the MnO4–solution into the 250 mL beaker so that it fills the reservoir’s tip. To do this, turn both valve handles to the vertical position for a moment, then turn them both back to horizontal.f.Discard the drained the MnO4–solution in the 250 mL beaker as directed.5.Calibrate the Drop Counter so that a precise volume of titrant is recorded in units of milliliters. Note: If you are using the stored calibration (20 drops per mL), then skip this step.a.Turn on the calculator and start the DATADROPprogram. Press CLEARto reset the program.
Advanced Chemistry with Vernier32 - 5Potentiometric Titration of Hydrogen Peroxideb. Select CALIBRATE DROPSfrom the Main screen.•If you have done a previous calibration with this particular apparatus, you can choose CALIBRATE DROPSand manually enter the drops/mL ratio. Select OKand proceed to Step 6.•If you want to perform a new calibration, continue with this step.c.Fill the reagent reservoir with titrant.d. Select CALIBRATE DROPSfrom the Main screen.e. Select CALIBRATE NOW.f.Open the bottom 2-way (on-off) valve to begin releasing drops from the vessel through the Drop Counter (the top valve finely adjusts the drop rate).g.Continue to release drops until there are between 9 and 10 mL of liquid in the graduated cylinder.h.Close the bottom valve on the vessel to stop the drops.i.Press ENTER.j.Type the precise volume of liquid in the graduated cylinder in milliliters and press ENTER.k.The number of drops/mL will be displayed. It may be helpful to record the value for that particular reagent reservoir for future titrations.l.Select OKto return to the Main screen.m. Discard the MnO4–solution in the graduated cylinder as indicated by your instructor and set the graduated cylinder aside.6.Assemble the apparatus.a.Place the magnetic stirrer on the base of the ring stand.b.Insert the ORP Sensor through the large hole in the Drop Counter.c.Attach the Microstirrer to the bottom of the ORP Sensor. Rotate the paddle wheel of the Microstirrer, making sure that it does not touch the tip of the ORP Sensor. d.Adjust the positions of the Drop Counter and reagent reservoir so they are both lined up with the center of the magnetic stirrer.e.Lift up the ORP Sensor, and slide the 100 mL beaker containing the H2O2solution onto the magnetic stirrer. Lower the ORP Sensor into the beaker.f.Adjust the position of the Drop Counter so that the Microstirrer on the ORP Sensor is just touching the bottom of the beaker.g.Adjust the reagent reservoir so its tip is just above the Drop Counter slot.h.Turn on the magnetic stirrer so that the Microstirrer is stirring at a fast rate.