DETERMINATION OF CHLORINE IN WATER

DETERMINATION OF CHLORINE IN WATER

A method for the measurement of chlorine in water containing from 0.06 to 1.6 ppm chlorine.

Equipment Required

1. Corning pH/ion analyser OR Corning pH meter with millivolt scale
2. Iodide ion selective electrode
3. Corning double junction reference electrode
4. Reference electrode lead

Reagents

1. Standard iodide solution
2. Reference electrode outer fill solution 1M KNO₃

Standard Preparation Standard solution A - mix equal volumes of:

5.6 x 10^-5 M   Potassium iodide

0.1M          Acetic acid

0.1M          Sodium acetate

0.001M        Sodium citrate

Standard solution B - mix equal volumes of:

5.6 x 10^-6M    Potassium iodide

0.1M          Acetic acid

0.1M          Sodium acetate

0.001M        Sodium citrate

Sample Preparation

Mix 10 ml of sample with 10 ml of standard solution A.

Method

Slope Factor (F): Immerse the electrodes in standard solutiSR B and record the mV response (EB). Rinse the electrodes in distilled water, immerse the electrodes in standard solution A and record the mV response (EA).

Calculate the slope factor from the equation:

F =  59.16 mV              (theoretical slope)

        EB - EA

Sample Measurement

Mix 10 ml of standard solution A with 10 ml of distilled water. Immerse the electrodes into the mixture and record the mV response (E₁).

Rinse the electrodes in distilled water, immerse the electrodes in the prepared sample solution and record the mV response (E₂).

The difference of the two measurement values is calculated (DE):

DE=E₂-E₁

Calculations

The chlorine concentration of the sample is calculated from the table of F x DE.

Expected Range;

The chlorine content of water is in the range 0.1 ppm to 1 ppm. TABLE OF F X ae