The concentration of chloride ions in a given water sample can be determined accurately using potentiometry by employing an ion-selective electrode ISE , specifically a chloride-selective electrode. The process involves the following steps:1. Calibration: Prepare a series of standard solutions with known concentrations of chloride ions. Measure the potential voltage of each solution using the chloride-selective electrode and a reference electrode. Plot the potential against the logarithm of the chloride ion concentration to create a calibration curve.2. Sample preparation: Collect the water sample and filter it if necessary to remove any suspended particles. If the sample has a very low or high ionic strength, it may be necessary to adjust it by dilution or addition of an ionic strength adjuster.3. Measurement: Immerse the chloride-selective electrode and the reference electrode in the water sample. Record the potential voltage of the sample.4. Determination of chloride ion concentration: Use the calibration curve to find the corresponding chloride ion concentration based on the measured potential of the water sample.Advantages of using potentiometry for determining chloride ions in water samples:1. High selectivity: Chloride-selective electrodes are highly selective for chloride ions, providing accurate measurements even in the presence of other ions.2. Wide concentration range: Potentiometry can be used to measure chloride ion concentrations over a wide range, from very low to very high concentrations.3. Fast and easy measurements: Potentiometry is a relatively simple and quick method for determining chloride ion concentrations in water samples.4. Non-destructive: The potentiometric method does not consume or alter the sample during the measurement process.Limitations of using potentiometry for determining chloride ions in water samples:1. Interference: Although chloride-selective electrodes are highly selective, some ions e.g., iodide, cyanide, and sulfide can interfere with the measurements, leading to inaccurate results.2. Sample preparation: The sample may require filtration or adjustment of ionic strength, which can be time-consuming and may introduce errors if not done correctly.3. Electrode maintenance: Chloride-selective electrodes require regular maintenance, such as cleaning and conditioning, to ensure accurate measurements.4. Temperature effects: Changes in temperature can affect the potential measurements, so temperature compensation or control may be necessary for accurate results.In conclusion, potentiometry using a chloride-selective electrode is a useful technique for determining the concentration of chloride ions in water samples. It offers high selectivity, a wide concentration range, and fast measurements. However, it has some limitations, such as potential interference from other ions, the need for sample preparation, electrode maintenance, and temperature effects.