Procedure:

Indicator Method - Pipette 20 ml or a suitable aliquot of sample into a 100-ml beaker. The sample size shall be so selected so that not more than 20 ml of titrant is needed for the titration. Determine the pH of water. If pH is less than, 3-7, add two drops of methyl orange indicator into the first sample beaker and titrate with standard 0•02 N sodium hydroxide solution until the color changes to the faint orange characteristic of pH 3'7. Record the volume of sodium hydroxide used. To the second sample beaker, add 2 to 3 drops of phenolphthalein indicator and titrate with 0•02 N sodium hydroxide solution to the appearance of faint pink color characteristics of pH 8'3. Record the volume used.

Potentiometric Method - Pipette 20 ml or a suitable aliquot of sample into a 100-mf beaker. Titrate with standard sodium hydroxide solution to pH 3•7 and pH 8'3. Record the volume of standard sodium hydroxide used. No indicator is required.