PRESENTATION ON

“HARDNESS OF WATER & ITS DETERMINATION”

ACKNOWEDGEMENT

I owe a great many thanks to a great many people who helped and supported me during the writing of this assignment.My deepest thanks to lecturer, the guide of the project, for guiding and correcting various documents of mine with attention and care. I would also thanks my institution and my faculty members without whom this project would have been a distant reality. I also extend my heartfelt thanks to my family and well wishers.

Constituents- 2 elements of H2

1 element of O2

3 states of water-

Solid, Liquid & Gas

Occurrence-Most

abundant & widely

distributed

3/4th of Earth’s crust

GENERAL INTRODUCTION

STRUCTURE• H20 is Polar i.e. ,it is partially charged• O2 has higher Electronegativity• H2O is a solvent• Forms 104.5deg angle• Bent shape/V-shape structure• H-bonding

HARDNESS OF WATER

Soap consuming power of water is called Hardness.

Ca2+/Mg2+ cationsCause Hardness

SoapSodium/Potassium salts of oleic acid, palmitic acid, stearic acid.

2C17H35COONa + CaCl2 (C17H35COO)2Ca +2NaCl(Sodium stearate)

2C17H35COONa + Ca(HCO3)2 (C17H35COO)2Ca + 2NaHCO3

Calcium stearate (Insoluble salt)

There are two types of hardness- Temporary hardness Permanent hardness

1>Temporary hardness- ~it is due to the presence of soluble salts of HCO3-

of Ca & Mg. ~it can be removed by boiling. In this the HCO3- are decomposed into insoluble CO32-

Ca(HCO3)2CaCO3 + H2O + CO2

(soluble) (insoluble)

TYPES OF HARDNESS

2. Permanent hardness It is due to sulphides,chlorides & nitrates of calcium, magnesium & other metals. CLASSIFICATION OF HARDNESS

Alkaline hardness Non-alkaline hardnesscarbonates,bicarbonates chlorides,sulphides &. & hydroxides of metals nitrates of metals

1.SOAP SOLUTION METHOD: Ca(HCO3)2+2C17H35COONa(C17H35COO)2Ca +NaHCO3

Ca bicarbonate sodium stearate Ca stearate

CaCl2 +2C17H35COONa(C17H35COO)2Ca+2NaCl

CaSO4+2C17H35COONa(C17H35COO)2Ca+Na2SO4

DETERMINATION OF HARDNESS

Hardness causing metal ions get precipitated.

When more sodium salt is added, lather is formed.

The aliquot is titrated against standard soap solution in alcohol.

End point indicates total hardness. The aliquot is boiled for 30 mins. Temporary hardness get removed(may

be due to the formation of CO2 which escapes)

2.EDTA method:

Burette:Na2[EDTA]H2[EDTA]H22- +2Na+

Flask:Ca2+/Mg2++[EBT]H[EBT]Ca +H+

(blue) (wine red)

Titration:[EDTA]H2

2-+[EBT]Ca[EDTA]Ca+[EBT]H {end

point} (wine red) colorless blue

Boil the aliquot for 30mins

Temporary hardness is removed

The remaining again titrated against Na2[EDTA]H2 complex

End point indicates permanent hardness

{Total hardness-Permanent hardness=temporary hardness}

CALCULATION OF TOTAL HARDNESS

Blockage of passage occurs when water is used for cooling due to scale deposition.

Hard water is harmful for drinking as it causes deposition of calcium in the bone joints.

It causes formation in boilers and pipes.

Hard water does not form any lather with soaps or detergents.

EFFECTS OF HARDNESS

Hard water is calculated in terms of calcium carbonate. It is because of the following reasons:

Molecular weight of CaCO3 is: 40+12+16x3=100

Most insoluble salt of Ca which is precipitated during water treatment processes.

Equivalent of CaCO3 = =[Mass of hardness producing substance x chemical equivalent of CaCO3

Chemical equivalent of hardness producing substance

= [Mass of hardness producing substance in mg/L]x multiplication factor

MEASUREMENT OF HARDNESS OF WATER

THANK YOU