Water is one of the most unique molecule known to man
We are comprised of mostly water
Unique properties of water molecules
A water molecule consists of two hydrogen atoms and one oxygen atom. The three atoms make an angle; the H-O-H angle is approximately 104.5 degrees. The center of each hydrogen atom is approximately 0.0957 nm from the center of the oxygen atom. In the solid state, the particles of matter are usually much closer together than they are in the liquid state. So if you put a solid into its corresponding liquid, it sinks. But this is not true of water. Its solid state is less dense than its liquid state, so it floats. Water behaves differently from most other chemical compounds. In almost all substances the atoms and molecules move closer together as they get colder. They then solidify. Water, however, attains its greatest density at four degrees Celsius because the water molecules are packed closest together at this temperature. Many freshwater lakes have a temperature of four degrees at their deepest point because the heavy water sinks to the bottom. But surprisingly, to reach the solid ice phase, the water molecules again move farther apart. This phenomenon is referred to as the water anomaly. Ice is lighter and floats at the surface. This is seen in the large ocean regions at polar latitudes, which are partly covered by ice. The reason for this anomaly lies in the unusual properties of the water molecule (H2O). Its oxygen atom (O) and the two hydrogen atoms (H) are asymmetrically arranged. This produces a dipole, a molecule with one negatively and one positively charged end.
Another unique property of water is its ability to dissolve a large variety of chemical substances. Water is sometimes called the universal solvent because it can dissolve so many things. water has the highest surface tension of any common liquid except mercury. It is the tendency of water molecules to attract to each other or cohere to each other at the surface of water. Because of this adhesion and cohesion properties water plays an important role in the internal transport system of plants and animals. The other widely-cited anomalous property of water is its high boiling point. a molecule as light as H2O “should” boil at around –90°C; that is, it would ideally exist in the world as a gas rather than a liquid if H-bonding were not present.
- Water is the most essential and pivotal resource. It is the largest single component of the human body, and is essential for life. The longest a person can survive with out water and food is about 8-10 days.
- The Stockholm International water Institute has estimated that each person on earth needs a minimum of 1000 m3 of water per year for drinking, hygiene and growing food for sustenance. Whether this water is available depends on where people live on the planet as water supply is extremely inequitable.
- Water scarcity affects every continent. For about 40% of the world population, lack of water is a constant threat. By 2025, almost half of the would population (around 4 billion people) will live under condition of severe water threat specially in Africa, Middle East and south Asia. UN estimates states that by 2025 around 1800 million people will be living in the countries or regions with absolute water scarcity and around two-thirds of the world population would be around stress condition.
- The situation is getting worse as the demand for water is doubling in every 20 years. In 20th century, global water consumption grew 6 fold.
- Colorado river is running dry and no more reaches the sea. Most of its water has been diverted to irrigated agriculture, so that in a normal year, no water at all reaches the river’s mouth.
- Yemen and Jordon are withdrawing 30% more from ground water resources than is being annually replenished. In Africa around 200 million people at present live in severe water stressed situation
- Half of the world’s wetlands have disappeared in the last 30 years. 20% of the fresh water species are engendered or extinct. Many important aquifers are seriously depleted. water table in many parts of the world are dropping at an alarming rate. Ground water recharge is a slow process, drained faster can not be replenished.
- The quantity of water used today for all purpose exceeds 4700 cubic kilometers per year. Agriculture is the largest user, consuming two-thirds of all water drawn from rivers, lakes and groundwater. Since 1960, water use for crop irrigation has risen by 60-70%. Industry uses about 20% available water and municipal sector (domestic use) uses about 10%
Task: Article review and note down 5 major points
Urban slum and water contamination in Kibera
|Natural Capital||Those goods and services that are not manufactured but have values to human, e.g. Soil, water, trees, living organisms etc.|
|Non-renewable energy||Exist in finite amount and are not renewed after they have been depleted, e.g. fossil fuels. These are forms of stored solar energy produced by photosysthesis (coal) and remains of organic life from millions of years ago, now being extracted and burned by humans.|
|Renewable energy||Can be used over and over again and are considered to be sustainable, e.g. Solar, wind, geothermal energy etc.|
|Replenishable resources||Are middle ground between renewable and non-renewable resources. They tend to be replaced over a long period of time. If the depletion rate is larger than recharge rate, the natural capital is depleted. E.g. Fuel wood.|
|Energy security||When all people in a society/country enjoy the uninterrupted supply of energy they require to meet their needs at an affordable price.|