To determine the concentration of Fe2+ ions in a water sample treated with iron-reducing bacteria using potentiometry, you will need to follow these steps:1. Prepare the water sample: Collect a representative water sample that has been treated with iron-reducing bacteria. Make sure the sample is well-mixed and free of any particulate matter.2. Prepare the potentiometric setup: You will need a potentiometer, a reference electrode such as a saturated calomel electrode or silver/silver chloride electrode , and an ion-selective electrode ISE specific for Fe2+ ions. Connect the electrodes to the potentiometer and calibrate the instrument according to the manufacturer's instructions.3. Standard solutions: Prepare a series of standard solutions containing known concentrations of Fe2+ ions. These solutions will be used to create a calibration curve, which will help you determine the concentration of Fe2+ ions in your water sample.4. Measure the potential of the standard solutions: Immerse the reference electrode and the Fe2+ ISE in each standard solution, and record the potential in millivolts displayed on the potentiometer. Make sure to rinse the electrodes with distilled water and blot dry between each measurement.5. Create a calibration curve: Plot the potential in millivolts on the y-axis and the logarithm of the Fe2+ concentration in moles per liter on the x-axis. The resulting curve should be linear, with a slope sensitivity close to the theoretical Nernstian slope for Fe2+ ions approximately 29.6 mV/decade at 25C .6. Measure the potential of the water sample: Immerse the reference electrode and the Fe2+ ISE in the water sample, and record the potential in millivolts displayed on the potentiometer.7. Determine the concentration of Fe2+ ions: Use the calibration curve to find the corresponding logarithm of the Fe2+ concentration for the measured potential of the water sample. Then, calculate the actual concentration of Fe2+ ions by taking the antilogarithm of the value.By following these steps, you can determine the concentration of Fe2+ ions in a water sample treated with iron-reducing bacteria using potentiometry.