3. INTRODUCTION :
● Human being can survive 3 days without drinking water.
● Water is an inorganic, transparent, tasteless, odorless, and
nearly colorless chemical substance, which is the main
constituent of Earth's hydrosphere and the fluids of all known
living organisms. It is vital for all known forms of life, despite
providing neither food, energy, nor organic micronutrients.
4. SOURCES OF WATER
There are three types of water sources
1. Rain water
2. Surface water
3. Ground water
5. RAIN WATER :
1.Caused due to evaporation of surface water and subsequent
precipitation
2. Most purest form of natural water
3. Dissolve impurities (SPM,CO2,SO2,NO2,)from atmosphere during
precipitation
4.Can be stored in underground reservoir tanks
6. SURFACE WATER :
The water that flows over the surface of earth and directly available
It includes :
1. River water 2. Lake water 3. Sea water
7. RIVER WATER:
● Comes from melting of snow,rain and
spring water
(coming from earth )
● Contains dissolved minerals/salts like
chlorides,sulphates,bicarbonates of
Na,Ca,Mg.
● Also contains impurities of sand rocks
and organic matter.
8. LAKE WATER :
● Contains organic impurities due to
decomposition of plants and
animals.
● Contains less amount of dissolved
minerals.
● Chemical composition is constant.
9. SEA WATER:
● Most impure form of natural water
● Dissolved salts are increased by
impurities thrown by rivers when they
join sea
● Contains 2000 times more dissolved
salts than other water
● Very saline- can not be used in
industries except for cooling
10. Ground water :
● Largest available source of freshwater
● Form of rain water Falling on earth
● Generally pure because it undergoes natural filtration during
percolation through soil pores
● Less likely to be contaminated by BACTERIA 🦠 but contains
dissolved salts
● To obtain in large quantity tube wells are used
11. HARDNESS OF WATER
“The property that prevents lathering of soap”
Cause of Hardness :
Presence of soluble salts of Ca, Mg or other heavy metals in water
● Hard water does not produce lather with soap
SOAPS
Generally soaps consists of Na salts of higher fatty acids such as
stearic acid,oleic acid,palmitic acid
Soaps are highly soluble in water thus exert their cleansing action
12. If Ca and Mg salts are present in water then these salts react with soap to
form insoluble white scum as ppt.e.g
2 C17H35COONa + CaSO4 > (C17H35COO)2Ca + Na2SO4
Sod .Stearate from hard Whiteppt
(Soap) water
2C17H35COONa + MgCl2 > (C17H35COO)2Mg + 2Nacl
Sod .stearate from hard white ppt
( soap) water
13. Types of hardness of water
● Temporary hardness of water (carbonate hardness)
● Permanent hardness of water (non-carbonate hardness)
14. Temporary hardness of water
Cause : due to the presence of bicarbonates of Ca and Mg also called as
Carbonate hardness of water.
Removal of temporary hardness of water:
On boiling, bicarbonates of Ca and Mg get decomposed into insoluble
carbonates which are deposited as insoluble precipitates at bottom of the
vessel
Ca(HCO3)2→ CaCO3 ↓+ Co2 ↑ + H2O
Mg(HCO3)2→ MgCO3↓ +Co2 ↑+ H20
15. PERMANENT HARDNESS OF WATER
Permanent hardness of water:
Cause: Due to the presence of sulfates and chlorides of Ca and Mg
Also called as non - carbonate hardness of water.
● Removal of permanent . Hardness - is not possible by boiling
● Special methods are used to remove permanent hardness of water
● Total hardness =temporary hardness+permanent hardness
16. BOILING OF WATER
Boiling is a very simple method of water disinfection.heating water to a high
temperature,100*C, kills most of the pathogenic organisms,particularly viruses and
bacteria causing waterborne diseases.
In order for boiling to most effective , the water must boil for
at least 20 minutes
17. Chlorination
Water chlorination is the process of adding
chlorine or chlorine compounds such as sodium
hypochlorite to water. This method is used to kill
bacteria, viruses and other microbes in water. In
particular, chlorination is used to prevent the
spread of waterborne diseases such as cholera,
dysentery, and typhoid.
18. BLEACHING POWDER
The process of chlorination has been used for a long time to purify the drinking
water.Bleaching powder in aqueous solution will produce CI- and OCI- ions.
Whereas OCI-ion acts as a good bleaching agent by killing the germs and bacteria
Bleaching powder which is chemically called as calcium oxychloride (CaOCI_2) is
an active agent which is used to kill germs and bacteria in drinking water
