To determine the concentration of lead Pb ions in a water sample using the method of polarography, you will need to follow these steps:1. Prepare the sample: Collect a representative sample of the water source and filter it to remove any suspended particles. Acidify the sample with nitric acid HNO3 to prevent precipitation of lead compounds and to stabilize the Pb ions.2. Prepare the polarographic cell: Set up a polarographic cell with a dropping mercury electrode DME as the working electrode, a reference electrode e.g., Ag/AgCl or calomel electrode , and a platinum counter electrode.3. Prepare the supporting electrolyte: Prepare a solution of a suitable supporting electrolyte, such as 0.1 M potassium chloride KCl or 0.1 M ammonium acetate NH4C2H3O2 . The supporting electrolyte should not interfere with the determination of lead ions.4. Add the sample to the polarographic cell: Add a known volume of the water sample to the polarographic cell containing the supporting electrolyte. Make sure the electrodes are properly immersed in the solution.5. Perform the polarographic analysis: Apply a potential sweep to the cell, starting from a potential more negative than the reduction potential of Pb II ions and ending at a potential more positive than the reduction potential of Pb II ions. Record the resulting current-potential curve polarogram .6. Identify the lead peak: Locate the peak corresponding to the reduction of Pb II ions to Pb 0 on the polarogram. The peak current ip is proportional to the concentration of lead ions in the sample.7. Calibration: Prepare a series of standard solutions containing known concentrations of lead ions and perform polarographic analysis on each standard solution. Plot the peak current ip as a function of the lead concentration to obtain a calibration curve.8. Determine the concentration of lead ions in the sample: Use the peak current ip obtained from the polarogram of the water sample and the calibration curve to determine the concentration of lead ions in the sample.Note that the actual concentration values and the specific experimental conditions may vary depending on the equipment and the method used. It is essential to follow the guidelines provided by the manufacturer of the polarographic instrument and to perform the analysis under controlled conditions to ensure accurate results.