Testing the hardness,presence of iron,chloride,fluoride etc.

    Testing the hardness, presence of iron, fluoride, chloride etc. depending upon the regional variation in drinking water and the study of causes of presence of these ions above permissible limit (if any).

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For Bicarbonate :

20 ml sample was taken in a conical flask and one drop of methyl orange was added as an indicator. The solution was turned into pink. Then it was titrated against 0.01 N H2SO4 from burette till the end point. The end point was colorless.

For total Hardness :

? ? ? ? ? ?10 ml of sample was diluted to about 20 ml was taken in a conical flask. Then 1-2 ml of buffer solution was added to maintain the pH of 10. After that 2-3 drops of EBT were added. It was titrated with standard EDTA solution from burette. Total hardness was expressed in parts of CaCO3 per million parts of water. The end point was blue color.

Total hardness as CaCO3 (mg/L) = (B.R ? M ? 100 ? 1000)/(ml of sample)

For Alkalinity :

Add 2 to 3 drops of bromocresol green indicator. Titrate until change in colour (blue to yellow, pH 4.9 to 4.3) is observed. Record total mL titrant used.

? ? ? ? ? ? ? ? ? ? ? Total alkanity, mg CaCO3/L = (B? N ? 50000)/(sample mL)

Calcium Hardness :

50mL well mixed sample in porcelain dish or conical flask was taken. 1mL sodium hydroxide was added to raise the pH to 12.0. Pinch of murexide indicator was added and titrated against EDTA solution end point was pink color turned to purple.

? ? ? ? ? ? ? ? ? ? ? ?Calcium as Ca+2 = ? ? ?(A ??400.5?1.05)/(ml of sample)

Mg Hardness

Get the values for Total Hardness and Ca Hardness determined by EDTA and calculate Mg hardness.

Magnesium hardness = Total hardness as CaCO3,mg/L ? Calcium hardness as CaCO3, mg/L

For Iron :

Took 5 mL water in a test tube. Then added 2 drops of dil. sulphuric acid. Then boiled the contents and allowed it to cool. Then added 2-3 drops of ammonium sulphocyanide. Appearance of orange colour indicated the presence of iron in water.

For Chloride :

Took 5 mL water in a test tube. Then added two drops of conc. nitric acid ?in it. Then boiled the contents of the test tube and allow it to cool. Then added two to three drops of AgNO3 solution to it. Appearance of curdy ppt indicated the presence of chloride in water. ?

For Fluoride :

Took 5 mL water in a test tube. Then added water, silver nitrate and dil. HNO3 to it. ?No precipitate indicated presence of fluoride ion in water