To determine the concentration of chloride ions in a sample of seawater using an ion-selective electrode ISE , you need to follow these steps:1. Calibration: Prepare a series of standard solutions with known concentrations of chloride ions. These solutions can be prepared by dissolving known amounts of a chloride salt e.g., sodium chloride in deionized water. Measure the potential voltage of each standard solution using the chloride ISE and record the values.2. Calibration curve: Plot the measured potentials in mV on the y-axis against the logarithm of the chloride ion concentrations in mol/L on the x-axis. Fit a linear regression line to the data points, and determine the slope and intercept of the line.3. Sample preparation: Collect a representative sample of the seawater and filter it if necessary to remove any suspended particles. Dilute the sample if needed to bring the chloride concentration within the range of the calibration curve.4. Sample measurement: Measure the potential of the seawater sample using the chloride ISE and record the value.5. Concentration calculation: Use the measured potential of the seawater sample and the calibration curve equation to calculate the logarithm of the chloride ion concentration. Then, find the antilogarithm 10^x to obtain the concentration in mol/L.6. Optional: If you diluted the seawater sample in step 3, multiply the calculated concentration by the dilution factor to obtain the original chloride ion concentration in the seawater.Keep in mind that the accuracy and precision of the measurement depend on the quality of the ion-selective electrode, the calibration curve, and the sample preparation. Additionally, interferences from other ions present in seawater may affect the measurement, so it is essential to use an ISE with high selectivity for chloride ions.