To determine the presence and concentration of chloride ions in a water sample using an ion-selective electrode ISE , follow these steps:1. Preparation: a. Gather the necessary equipment: chloride ion-selective electrode, reference electrode, pH/mV meter, magnetic stirrer, and calibration standards. b. Prepare the calibration standards: Make a series of chloride ion solutions with known concentrations e.g., 1, 10, 100, and 1000 mg/L using a chloride salt, such as sodium chloride NaCl , dissolved in deionized water.2. Calibration: a. Connect the chloride ISE and reference electrode to the pH/mV meter. b. Immerse the electrodes in the first calibration standard lowest concentration and allow the solution to stir gently. c. Wait for the mV reading to stabilize, then record the mV value and the corresponding chloride concentration. d. Repeat steps b and c for each calibration standard. e. Plot the mV values against the logarithm of the chloride concentrations to create a calibration curve. The slope of the curve should be near the theoretical Nernstian slope of -59.16 mV/decade at 25C.3. Sample measurement: a. Rinse the electrodes with deionized water and immerse them in the water sample to be tested. b. Allow the sample to stir gently and wait for the mV reading to stabilize. c. Record the mV value of the sample.4. Determination of chloride concentration: a. Using the calibration curve, find the corresponding logarithm of the chloride concentration for the recorded mV value of the sample. b. Calculate the actual chloride concentration by taking the antilogarithm 10^x of the value obtained in step a.The concentration of chloride ions in the water sample is the value obtained in step 4b.