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Water

Water molecules are polar and exhibit unique properties such as maximum density at 4 degrees Celsius, high heat capacity, and the ability to dissolve many substances. Common pollutants include phosphates, nitrates, and organic waste, while water hardness can be temporary or permanent due to calcium and magnesium salts. Treatment methods for domestic water include flocculation, sedimentation, filtration, and chlorination, with softening methods like boiling, adding sodium carbonate, and distillation to remove hardness-causing minerals.

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3 views2 pages

Water

Water molecules are polar and exhibit unique properties such as maximum density at 4 degrees Celsius, high heat capacity, and the ability to dissolve many substances. Common pollutants include phosphates, nitrates, and organic waste, while water hardness can be temporary or permanent due to calcium and magnesium salts. Treatment methods for domestic water include flocculation, sedimentation, filtration, and chlorination, with softening methods like boiling, adding sodium carbonate, and distillation to remove hardness-causing minerals.

Uploaded by

ethanthakurdin2009
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© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Water molecules are polar.

The positively charged ion molecules are attracted to the slightly


negatively charged oxygen molecules and the bond is very strong.

Properties of water:
 Water has a maximum density of 4 degrees Celsius. When water is cooled to 4 degrees
Celsius it contracts and becomes dense. If it is further cooled below that temperature it
expands and becomes less dense and eventually ice forms at 0 degrees Celsius.

 Water requires a lot of heat for vaporization: water requires a lot of heat to convert it from
liquid to its vapor. When it evaporates, it removes a lot of heat energy as well.

 Water has a high heat capacity: water requires a lot of energy to increase its temperature
by 1 degree Celsius.

 Water has a high boiling: water boils at 100 degrees Celsius as compared to other
molecules of similar size

 Water can dissolve a large number of substances: Due to its polar nature, water is able to
dissolve ionic or polar covalent substances.

Common pollutants of water: Phosphates and nitrates, organic waste, fertilizers etc.
 Leaching: Leaching refers to when water seeps into the soil and dissolve the water-
soluble minerals and carry it further from the roots of plants causing the soil to be
considered less fertile.
 Hard water: Hard water is formed by adding calcium and magnesium salts. It causes the
water to not easily lather with soap unlike soft water. Some disadvantages are it is wastes
soap and forms scum.

There are 2 types of water hardness:


- Temporary: This occurs when calcium hydrogen carbonate and magnesium hydrogen
carbonate is added to water. It can be converted to soft water by boiling.

- Permanent: This occurs when calcium sulfate and magnesium sulfate is added to
water. It cannot be converted by boiling.

Treatment of water for domestic use:


 Flocculation: This involves mixing the water with chemicals such as alum to cause solid
impurities in water to clump up and form sediments called floc.

 Sedimentation: the floc is then left to settle at the bottom

 Filtration: the floc is filtered out along with bacteria and viruses

 Chlorination: this involves adding monochloramine or chlorine gas to further kill the
remaining microorganisms.

Methods used to soften water:


To soften water, the dissolved magnesium and calcium salts must be removed.

 Boiling: this removes temporary hardness by decomposing only calcium hydrogen


carbonate into carbon dioxide, water and calcium carbonate.

 Adding sodium carbonate: the sodium carbonate causes the calcium and magnesium to be
precipitated out as insoluble.

 Distillation: evaporating water and collecting the vapor and leaving behind dissolved
salts and microorganisms.

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