Химия. Экология. Медицина



жүктеу 2.07 Mb.
бет52/61
Дата22.02.2016
өлшемі2.07 Mb.
1   ...   48   49   50   51   52   53   54   55   ...   61

MINERALS ARE EARTH'S TREASURES

Manik Puri, group 23. Science adviser is Olga Levashova.


Minerals are substances formed naturally in the Earth. They have a definite chemical composition and structure. There are over 3000 minerals known. Some are rare and precious such as gold and diamond, while others are more ordinary, such as quartz. Do you know of any more examples of minerals from the Earth?

Like all substances, minerals are composed of elements.

There are only about a hundred elements, and they are the basic building blocks of everything around us. They can be found either in their pure form or chemically combined with other elements to make compounds. A compound is two or more elements chemically joined together.

In this discussion, we hope to answer the following questions:

• What constitutes a mineral resource and an ore?

• What determines whether or not a mineral sources is economical to exploit?

• How are mineral resources found and exploited?

• What happens when a mineral resource become scarce as a result of human consumption?

• What are the adverse effects of exploiting mineral resource.

Mineral Resource is a volume of rock enriched in one or more useful materials. In this sense a mineral refers to a useful material. Here the word mineral can be any substance that comes from the Earth.

Finding and exploiting mineral resources requires the application of the principles of geology. Some minerals are used as they are found in the ground, i.e. they require no further processing or very little processing. For example - gemstones, sand, gravel, and salt (halite). Most minerals must be processed before they are used.

For example:

Iron is the found in abundance in minerals, but the process of extracting iron from different minerals varies in cost depending on the mineral.

Aluminum is the third most abundant mineral in the Earth's crust. It occurs in the most common minerals of the crust - the feldspars (NaAlSi3O8, KalSi3O8, & CaAl2Si2O8, but the cost of extracting the Aluminum from these.

For every substance we can determine the concentration necessary in a mineral deposit for profitable mining. By dividing this economical concentration by the average crustal abundance for that substance, we can determine a value called the concentration factor.

Because different types of mineral deposits form in different environments, plate tectonics plays a critical role in the location of different geological environments.

Ores are located by evidence of metal enrichment. Geologists look for hints in rocks exposed near the surface, for example, the enrichment process often results in discoloration of the soil and rock. When such hints are found, geophysical survey's involving measuring gravity, magnetism, or radioactivity are conducted. Geochemical surveys are conducted which analyze the composition of water, sediment, soil, rocks, and sometimes even plants and trees.

Once it is determined that a valuable material could be present, the deposit is assessed by conducting core drilling to collect subsurface samples, followed by chemical analysis of the samples to determine the grade of the ore. If the samples show promise of being economic to mine, then plans are made to determine how it will me mined.

Because the processes that form ores operate on geologic time scales, the most economic mineral resources are essentially nonrenewable.New deposits cannot be generated in human timescales. But, as mentioned previously, as the reserves of materials become depleted it is possible to find other sources that are more costly to exploit. Furthermore, mineral resources are not evenly distributed.

Some countries are mineral-rich; some are mineral-poor. This is a particular issue for strategic mineral resources.

Extraction and processing has large environmental impacts in terms of such things as air quality, surface water quality, groundwater quality, soils, vegetation, and aesthetics. Acid mine drainage is one example, Sulfide minerals newly exposed to Oxygen and water near the surface create sulfuric acid. Rainwater falling on the mine tailings becomes acidified and can create toxic conditions in the runoff. This can mobilize potentially dangerous heavy metals and kill organisms in the streams draining the tailings.


THE CONTRIBUTION OF GREAT CHEMIST TO THE DEVELOPMENT OF MODERN CHEMISTRY

Sonali Sharma, group 24. Science adviser is Larisa Lukyanova.


A chemist is a scientist trained in the study of chemistry.Chemists study the composition of matter and its properties .Chemist carefully describe the properties they study in term of qualities with detail on the level of molecules and their component atoms.

The timeline is consider to have become a full-fledged science with the work of antione Lavoisier,w ho developed a law of conservation of mass that demanded careful measurments and quantitative observation of chemical phenomena.The history of chemistry inbits modern form arguably began with the english scientist Robert Boyle,through its roots can be traced back to the earliest recorded history.

Chemistry is an old science born out of the all chemist's lab it has come to represent the study of interactions between matter and energy.The sister science to physics,chemistry,focusses atomic and sometimes subatomic interaction.

Some great chemists who contribute in development of modern chemistry:

Dmitri Mendeley- Every one in the world chemistry known the name known as father of the periodic table of the elements.Mendleve born in russian through many struggles become a science master.He become professor of chemistry at St.Perterburgs Technical Insitute in 1860's.Soon after this he published his observation on the combination ofwater and alcohal.

Julian Banzon-- Dr.Banzon was born in the philippines and earned his bachelors degree at the university of the philippines. Banzon studies organic material and through his experimentation he discoverd that many products native to his homeland produced ethyl ester fuels.........

ADVANCE IN MEDICINE

Jokichi Takamine-Born in japan in the mid 1800's.Takamine received his formal education in japan.His post graduate work occured in scotland . While working with an artificial fertilizer company,he isolated an enzyme Takadiastase which is used in sake fermentation.Dr.Takamine isolated and purified the harmone adrenaline from animals gland. He was the first to accomplish this and his discovery helped advance treatment of asthma.

The history of chemistry encompasses a span of time reaching from ancient history to the preasent. By 1000 BC ancient civilization used technologies that would eventually from the basis the various branches of chemistry. Example include extracting metals from ores,making pottery and glazes,fermentation beer and wine,extracting chemicals from plants for medicine and perfume.

In the 17th century,a synthesis of the ideas of these two disciplines,that is the deductive and the experimental leads to the development of a process of thinking known as the scientific method. With the introduction of the scientific method,the modern science of chemistry was born by the very great chemists.



1   ...   48   49   50   51   52   53   54   55   ...   61


©dereksiz.org 2016
әкімшілігінің қараңыз

    Басты бет