Hydrosphere

Objectives

At the end of the session the students should be able to:

1. Can discuss the importance and unique properties of water.

2. Can identify the different causes of water pollution.

3. Can draw and explain the hydrologic cycle.

4. Can enumerate the ways how to prevent water pollution.

Hydrosphere

• Water Layer

• ¾ of the Earth’s surface

• Water differs from other matter because it can be present in all 3 phases of matter without changing its chemical composition.

1. Liquid phase 

   • ex. water 

2. Solid phase 

   • ex. ice 

3. Gaseous phase 

   • ex. water vapor / steam 

Properties of Water 

1. Tasteless 

2. Odorless 

3. Transparent  

4. High surface tension 

• Surface tension - the property of the surface of a liquid that allows it to resist an external force. 

5. Capable of adhesion and cohesion 

• Adhesion - Force of attraction between two sustances.

• Cohesion - Force of attraction of molecules of the same substance. 

6. Exhibit capillary action 

• Capillary action - The tendency of water to move up against the force of gravity. 

7. Miscible 

• Miscible - The ability of a substance to mixed with other substance. 

8. Universal solvent 

• Water able to dissolve a large number of different chemical compounds.

• Hydrophilic substance 

Ex.  Salts, sugars, alkalis, some gases such as O2 and CO2

• Hydrophobic substance

Ex.  Fats and oils 

9. High specific heat. 

• Specific heat is the amount of energy required to change the temperature of a substance. 

• Water can absorb large amounts of heat energy before it begins to get hot while releases heat energy slowly when situations cause it to cool. 

10. Neutral pH 

• Water in a pure state has a neutral pH. 

• Pure water is neither acidic nor basic. 

• Water changes its pH when substances are dissolved in it. 

• Rain has a naturally acidic pH of about 5.6 because it contains natural derived carbon dioxide and sulfur dioxide. 

Water Pollution

• Water pollution is the contamination of water bodies such as lakes, rivers, oceans, and groundwater that affects living organisms. 

Causes of Water Pollution

1. Pathogens

• Disease-causing microorganisms

2. Chemical contaminants

• Organic water pollutants - manure/sewage

• Inorganic water pollutants - arsenic, fluoride, iron, nitrate

• Macroscopic pollution - trash

3. Thermal pollution

• The rise or fall in the temperature of a natural body of water. 

Water Cycle / Hydrologic cycle

Processes involved in the water cycle

1. Evaporation – conversion of water to vapor

2. Transpiration –  process of releasing water from the plants

3. Condensation - process of cloud formation.

4. Precipitation – rain formation

5. Run-off – occurrence of excess water from watershed that flows on the surface

6. Infiltration – Movement of water from the upper ground to the lower ground.

7. Sublimation – process of snow or ice changing into water vapor

8. Snow-melt – changing ice or snow into liquid state water.

How to Reduce Water Pollution?

• Proper waste management

• 3 R’s  to prevent water pollution

• Reuse water by the water treatment

• Reduce – Say no to water pollution

• Recycle – Recycle water (by water treatment)