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Water (H2O) is a precious compound
that as far as our knowledge goes is only found on earth. It is made up of two atoms of hydrogen and one atom of oxygen. Water
is required for all forms of life, in plants and animals, and is continually recycled. Uses for water include for drinking,
cleaning, and being a swimmer’s paradise. Needless to say, water is used is almost every aspect of human life. Water
is present in all three states, as a solid liquid or gas depending on pressure and temperature. As a solid, it is found as
ice most abundantly in glaciers and icebergs. For water to be a solid, the temperature must be below 0 degrees Celsius, where
it will freeze. In a solid, the water molecules simply stop moving because of the very low temperatures. Water as a liquid,
is found at room temperature. As a liquid, it is very versatile and forms to fill bodies of water. It is also a part of all
kinds of chemical reactions because of its very adaptable properties. As a gas, water is carried high into the atmosphere
where it becomes rain. For solid or liquid water to become a gas, the temperature must heat up. Heat causes the molecules
to speed up enough that it becomes invisible and light enough to float in the atmosphere.
Water is an abundant resource and is commonly
used in everyday events. However, the earth only contains a small amount of freshwater, which is being used faster then it
is replenished. Sources of freshwater only make up 3% of the total amount of water on earth. Ocean water covers about 70%
of the earth with water and makes up 97% of all the water on earth, but is composed of massive amount of salts. The amount
of salts in seawater is measured on a scale called salinity. Salinity measures the amount of salt in grams found in one kilogram
of water. The salts are so abundant that this water is undrinkable and harmful with out proper treatment to remove the salts.
The treatment is desalination. The process of desalination involves eliminating the salts from the water. One such method
is distillation. Distillation involves boiling the water to high temperatures as for the water to become a gas. The salt cannot
reside in a gaseous form and therefore, doesn’t rise like the gaseous H2O. The water as a gas, which is referred to
as water vapor is collected and returned to room temperature where it reverts back to a liquid. Another, more energy efficient
method of desalination is reverse osmosis. This method sends seawater through a larger pipe containing a smaller semi permeable
one. Pressure pushes the water through into the semi permeable pipe which does not accept the salt molecules because of their
larger size, hereby collecting pure water.
The water cycle is known as the hydrologic
cycle and begins in the most abundant source of water on earth- the oceans. It
is biogeochemical and involves the hydrosphere, lithosphere and atmosphere. This cycle deals with how water is stored in the
earth’s environment and how it is distributed to all extents of the earth. Water molecules in the ocean and large bodies of water, are always moving and due to their abundance, are estimated to remain there for about 1000
years, before continuing in the cycle. Along with ocean water, moisture in the soil,
which is estimate to be there for about 70 days, are evaporated into the atmosphere. Evaporation
is the process, when heat energy causes a liquid to become a gas. When water molecules from large bodies of water and soil
are evaporated, their gaseous molecules known as water vapor float up into the atmosphere where they start to cool. When the
water vapor is finally cooled off, the gaseous molecules turn back into liquid, and merging with dust particles in the air,
form clouds. This change in the state of matter is called condensation. The newly formed clouds hover above the hydrosphere and lithosphere, in the atmosphere, all the
while the molecules are combining and become larger. When the molecules become too large, they can no longer defy gravity
and fall to the earth as precipitation. Precipitation refers to rain, snow and hail. There are three different forms depending on the temperature. The process of condensation
and precipitation is estimated to take approximately 8 days. On the lithosphere, water runoff
occurs, where the water travels according to land mass and gravity. Runoff flows the water into the soil, rivers and lakes. Here, the water remains in the rivers for sixteen days before it is returned to the ocean. The
water molecules in the soil and lakes have the opportunity to be evaporated as well as returning to the ocean, where the cycle
continues.
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