What is water in the context of environmental factors?
Water is the most potent solvent and has a great significance in supporting life.The life on earth is possible just because of presence of water in all three forms of solid, liquid and gas. The water molecule is formed of two molecules of hydrogen and one molecule of oxygen. Water can favor biological activities because of the presence of certain properties like:
Cohesiveness and Surface Tension.
The force of attraction is present between the water molecules because of which molecules do not move apart yet can flow freely and take the shape of the vessel is called cohesiveness. The surface tension of the water is very high and this surface forms a thin, film on the outer surface of water present. Various solid particles like sand and pollen float over the water layer because of the surface tension.
The transparent nature of the water permits certain wavelength of light penetrating through it. This make the aquatic and marine life existence possible as the living beings inside takes the sunlight which is dissolved and permitted by water.
The temperature change in water is much less as compared to land and air, Due to this unique thermal property the temperature beneath water is maintained almost constant. The temperature of water drops very slowly on losing heat.
As compared to other liquids, the rate of cooling and heating of water is relatively low. This is because the water molecules are linked with each other by hydrogen bond. The specific heat of water is 4.18 joules, which means 4.18 joule of energy is required to heat one gram of water by one degree.
Solubility of Gases.
The aquatic and marine life is totally dependent upon water dissolved oxygen for their survival. The phytoplanktons require carbon-dioxide for synthesis, which is contributed by respiration and decomposition of aquatic organisms. Carbon-dioxide diffuses into the atmosphere and dissolves in water to form carbonic acid, which affects the pH of water.
Phases of Water.
Water has the unique property of existing in all the three states of matter and can be interchanged to each other, by addition or removal of heat energy to convert one gram of liquid into ice, it requires removal of 80 calories of heat energy and to convert one gram of water in to steam, it requires in take of 540 calories of heat energy.
Density of Water in relation to Temperature.
When the temperature falls, the water molecules come closer, making the water dense. The maximum density is observed at 4 degree Celsius. Although water is still liquid and the water molecules are in a free moving state. When the temperature falls below 4 degree, the bonds between the water molecules lose their flexibility and are located at a distance from each other, keeping some space for air pockets.
This makes ice lighter than water, making ice float over it. The top layer of water freezes retaining the liquid state beneath, which is important for survival of under water organisms during winters.