Химия. Экология. Медицина

жүктеу 2.07 Mb.
өлшемі2.07 Mb.
1   ...   53   54   55   56   57   58   59   60   61


Saad Ayman Nachaat, group 2. Science adviser is Svetlana Kozub.

A mineral can be defined as a naturally occurring inorganic solid that possesses an orderly internal structure and a definite chemical composition. Some people, like physicists, might be guilty of picking up a rock and calling it a mineral. The term "rock" is less specific, referring to any solid mass of mineral or mineral-like material. Common rocks are often made up of crystals of several kinds of minerals.

There are some substances, like opal, which have the appearance of a mineral but lack any definite internal structure, are sometimes called "mineraloids". Lutgens and Tarbuck give the following list of essential characteristics of a "mineral":

1. It must occur naturally.

2. It must be inorganic

3. It must be a solid

4. It must possess an orderly internal structure, that is, its atoms must be

arranged in a definite pattern.

5. It must have a definite chemical composition that may vary within specified


Mineral classes: аs the composition of the Earth's crust is dominated by silicon and oxygen, silicate elements are by far the most important class of minerals in terms of rock formation and diversity.

Non-silicates,Native elements

Native elements are those that are not chemically bonded to other elements.

The sulfide minerals are chemical compounds of one or more metals or semimetals with a sulfur; tellurium, arsenic, or selenium can substitute for the sulfur.

Oxide minerals are divided into three categories: simple oxides, hydroxides, and multiple oxides. Simple oxides are characterized by O2-primarily ionic bonding.

The halide minerals are compounds where a halogen (fluorine, chlorine, iodine,

and bromine) is the main anion.

The carbonate minerals are those were the main anionic group is carbonate, [CO3]2− Carbonates tend to be brittle, many have rhombohedral cleavage, and all react with acid.

The sulfate minerals all contain the sulfate anion, [SO4] transparent to translucent, soft, and many are fragile.

The phosphate minerals are characterized by the tetrahedral [PO4] the structure can be generalized, and phosphorus is replaced by antimony, arsenic,or vanadium.

The Strunz classification includes a class for organic minerals.These rare compounds contain organic carbon, but can be formed by a geologic process.

For example, whewellite, CaC2O4*H2O is an oxalate that can be deposited in hydrothermal ore veins.


Sara Sofiane, group 2. Science adviser is Svetlana Kozub.

A mineral is a naturally occurring substance that is solid and stable at room temperature, representable by a chemical formula, usually abiogenic, and has an ordered atomic structure. It is different from a rock, which can be an aggregate of minerals or non-minerals and does not have a specific chemical composition. The exact definition of a mineral is under debate, especially with respect to the requirement a valid species be abiogenic, and to a lesser extent with regards to it having an ordered atomic structure. The study of minerals is called mineralogy.

Petroleum is a naturally occurring, smelly, yellow-to-black liquid consisting of a complex mixture of hydrocarbons of various molecular weights and other liquid organic compounds, that are found in geologic formations beneath the Earth's surface. The name Petroleum covers both naturally occurring unprocessed crude oils and petroleum products that are made up of refined crude oil. A fossil fuel, petroleum is formed when large quantities of dead organisms, usually zooplankton and algae, are buried underneathsedimentary rock and undergo intense heat and pressure.

Petroleum is recovered mostly through oil drilling. This comes after the studies of structural geology (at the reservoir scale), sedimentary basin analysis, reservoir characterization (mainly in terms of the porosity and permeability of geologic reservoir structures). It is refined and separated, most easily by boiling point, into a large number of consumer products, from gasoline (petrol) and kerosene to asphalt and chemical reagents used to make plastics andpharmaceuticals.Petroleum is used in manufacturing a wide variety of materials, and it is estimated that the world consumes about 90 million barrels each day.

The use of fossil fuels such as petroleum can have a negative impact on Earth's biosphere, releasing pollutants and greenhouse gases into the air and damaging ecosystems through events such as oil spills. Concern over the depletion of the earth's finite reserves of oil, and the effect this would have on a society dependent on it, is a concept known as peak oil.

In its strictest sense, petroleum includes only crude oil, but in common usage it includes all liquid, gaseous, and solid hydrocarbons. Under surface pressure and temperature conditions, lighter hydrocarbons methane, ethane, propane and butane occur as gases, while pentane and heavier ones are in the form of liquids or solids. However, in an underground oil reservoir the proportions of gas, liquid, and solid depend on subsurface conditions and on the phase diagram of the petroleum mixture.

An oil well produces predominantly crude oil, with some natural gas dissolved in it. Because the pressure is lower at the surface than underground, some of the gas will come out of solution and be recovered (or burned) as associated gas or solution gas. A gas well produces predominantly natural gas. However, because the underground temperature and pressure are higher than at the surface, the gas may contain heavier hydrocarbons such as pentane, hexane, and heptane in the gaseous state. At surface conditions these will condense out of the gas to form natural gas condensate, often shortened to condensate. Condensate resembles petrol in appearance and is similar in composition to some volatile light crude oils.

The proportion of light hydrocarbons in the petroleum mixture varies greatly among different oil fields, ranging from as much as 97 percent by weight in the lighter oils to as little as 50 percent in the heavier oils and bitumens.

The hydrocarbons in crude oil are mostly alkanes, cycloalkanes and various aromatic hydrocarbons while the other organic compounds contain nitrogen, oxygen and sulfur, and trace amounts of metals such as iron, nickel, copper and vanadium.

1   ...   53   54   55   56   57   58   59   60   61

©dereksiz.org 2016
әкімшілігінің қараңыз

    Басты бет