CHAPTER ONE

1.0 INTRODUCTION

Water is a chemical compound with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at standard ambient temperature and pressure, but it often co-exists on earth with its solid state ice, and gaseous state (water vapor or steam). 

Water also exists in a liquid crystal state near hydrophilic surfaces. Water covers 71% of the earth’s surfaces and is vital for all known forms of life. On earth’s surface 96.5%of the planet’s water is found in oceans, 1.7% in ground water, 1.7% in glaciers and the ice caps of Antarctica and Greenland, a small fraction in other large water bodies, and o.oo1% in the air as vapor, clouds (formed of solid and liquid water particles suspended in air) and precipitation. Only 2.5% of the earths water ground water. Less than 0.3% of all freshwater is in rivers, lakes, and the atmosphere, and an even smaller amount of the earth’s fresh water (0.003%) is contained within biological bodies and manufacture products.

Water on earth moves continually through the water cycle of evaporation and transportation (evapotranspiration) condensation, precipitation, run off, usually reaching the sea. Traporarion and transpiration contribute to the precipitation over land.

1.1 PROPERTIES OF WATER

THE MAJOR CHEMICAL AND PHYSICAL PROPERTIES OF WATER.

- Water is a liquid at standard temperature and pressure. It is tasteless and odorless. The intrinsic colour of water and ice is a very slight blue hue, although both appear colorless in small quantities.

- Water is transparent in the visible electromagnetic spectrum. Thus aquatic plants can live in water because sunlight can reach them. Infrared light is strongly absorbed by the hydrogen – oxygen or OH bonds.

- Water is a good polar solvent and is often referred to as the universal solvent. Substances that dissolve in water, e.g. salts, sugars, acids, alkalis and some gases especially oxygen, carbon dioxide (carbonation) are known as hydrophilic (water fearing) substance.

- Most of the major components in cells (proteins, DNA and polysaccharides) are also dissolved in water.

- Pure water has a low electrical conductivity, but this increase we with the dissolution of a small amount of ionic material such as sodium chloride.

- The boiling point of water (and all other liquids) is dependent on the barometric pressure. For example, on the top of Mt. Everest water boil at 680c (154 o f) compared to 100oc (212) at sea level. Conversely, water deep in the ocean near geothermal vents can reach temperature of hundreds of degrees and remain liquid

At 4181.3J (kg.k), water has a high specific heat capacity, as well as a high heat of vaporization (40.65KJ. mol-1). Both of its molecules. These two unusual properties allow water to moderate earth’s climate by buffering large fluctuation in temperature

- The density of liquid water is 1,000 kg/m3 (62.43 1b/cu ft) at 4oc.

- Water forms an zoetrope with many other solvents.

- Water can be split by electrolysis into hydrogen and oxygen.

- As an oxide of hydrogen, water is formed when hydrogen or hydrogen – containing compound burns or react with oxygen or oxygen containing compounds

1.2 SOURCES OF WATER

Rain water, oceans, river, lakes, streams, ponds, and spring are natural sources of water.

Rain water: Rain water collects on the earth in the form of surface water and underground water.

Surface water: Water present on the surface of the earth in the form of oceans, rivers and lakes comes from rain and streams are called surface water. The water in rivers and lakes comes from rain and melting of snow on mountains. Rivers flow into the sea.

Underground water: Some of the rainwater seeps through the soil on the nonporous rocks. Sometimes due to high pressure this water sprouts out in the form of springs. It can be obtained by digging wells, sinking tubes well e.t.c. 

1.3 TYPES OF WATER

1. Hard water: This is saturated with calcium, iron, magnesium and many other inorganic minerals, All water in lakes, river on the ground, in deep wells, is classified as hard water.

2. Boiled helps remove some of the germs, but concentrates the inorganic minerals

3. Raw water: This as not been boiling. Raw water maybe hard (as calcium hardened water)or soft as rain water. It contains millions of germs and viruses. some of these viruses. Some of these viruses and bacteria may adversely affect the thyroid gland, the liver and other vital body organs.

4. Rain water: This has been condensed from the clouds. The first drop is distilled water. But when it falls as rain, it picks up germs, dust, smoke, minerals, strontium 90, lead and many other atmospheric chemicals.

5. Snow water: this is frozen rain; freezing does not eliminate any germs. All snow and you will find it saturated with dirt, inorganic minerals, germs and viruses.  

6. Filtered water: This water has passed through a fine strainer, called a filter. Some calcium and other solid substances are kept in the filter; there is no filter made which can prevent germs from passing through its fine meshes.

7. Soft water: This is a soft in comparison which water which is harder. It may contain many trace minerals and chemicals, viruses and bacterial.

8. Reverse Osmosis: This is a system of water purification which allows pre-filtered water to be forced through a semi-permeable membrane to separate impurities from our drinking water.

9. De-ionized water: A process of exchanging may “hard” ions for “soft” the total icons are still present. The end result is the same. But water has the appearance of being distilled. 

10. Distilled water: This is water that has first been turned into stream so that all of its impurities are left behind