Classified in Language

Written at on English with a size of 24.55 KB.


The stoichiometry

In chemistry, is the calculation of the quantitative relationships between reactants and products during a chemical reaction. These relationships can be deduced from the atomic theory, although historically spelled out without reference to the composition of matter, according to different laws and principles.

The first to set out the principles of stoichiometry was Jeremias Benjamin Richter (1762-1807) in 1792. He wrote:

The stoichiometry is the science that measures the quantitative proportions or mass ratios in which chemical elements are involved.
Mixture, stoichiometric ratios and Conditions
When reactants of a reaction are in amounts proportional to their stoichiometric coefficients is said:
• The mixture is stoichiometric;
· The reagents are in stoichiometric proportions;
• The reaction takes place at stoichiometric conditions;
The three expressions have the same meaning.
Under these conditions, if the reaction is complete, all the reagents are consumed giving the stoichiometric quantities of products concerned. If not in this way there will be the limiting reagent is the one in lower proportion than it is based on work all calculations.
· How much oxygen is needed to react with 100 grams of carbon to produce carbon dioxide?
Atomic mass of oxygen = 15.9994.
Atomic mass of carbon = 12.0107.
The reaction is:
To form a molecule of carbon dioxide, we need a carbon atom and two oxygen atoms, or what is the same, one mole of carbon and two oxygen mole.
Solving for x:
Performed operations:

Liquefied natural gas (LNG) is natural gas that has been processed to be transported in liquid form. It is the best alternative to monetize reserves in remote places where it is not economical to carry the gas to market directly either by pipeline or power generation. Natural gas is transported as a liquid at atmospheric pressure and -161 ° C which reduces the liquefaction at 600 times the volume of gas transported.
Reasons for liquefaction of natural gas LNG
Natural gas is usually transported using pipelines, but for long distances, it is more economical to use ships. Need for transportation and liquefy, as at room temperature and atmospheric pressure occupies a considerable volume. The liquefaction process reduces the volume of natural gas over 600 times its original volume. About half the known oil reserves today are natural gas fields. They are often located in regions with low demand for gas. However, liquify, can be transported safely to its target market using vessels, similar to crude oil.
Environmental Impact
LNG has the lowest environmental impact of all fuels for its high content of hydrogen. LNG spills dissipate in the air and contaminate the soil or water. As a vehicle fuel, reduces emissions of nitrogen oxides (NOx) by 70%, and produces no sulfur compounds and particulates. For electricity generation emissions of sulfur dioxide, SO2 are virtually eliminated and CO 2 emissions are reduced by 40%.
All production and transport systems and the processing plant, are designed to prevent leaks and fire prevention; is the case of LNG transfer systems to and from ships, shipping or re-vaporization (or re-gasification) of LNG. There are some design differences on gas plants, but environmental considerations, safety and health are the same or more stringent. The main risks are the low temperature (cryogenic risk) and its flammability.
The liquefied petroleum gas (LPG) is the condensable gas mixture present in natural gas or dissolved in oil. The components of LPG, although temperature and pressure are gases, they are easy to condense, hence its name. In practice, one can say that LPG is a mixture of propane and butane.
Propane and butane are present in crude oil and natural gas, while some was obtained during the refining of petroleum, especially as a byproduct of the fractional distillation catalytic (FCC, for its acronym in English Fluid Catalytic Cracking).
Use of Liquefied Petroleum Gas LPG
The major uses of LPG are:
· Collection of olefins, used for the production of numerous products, including most plastics.
· Fuel cars
· Fuel refinery.
· Domestic Fuel (via bottles or distribution networks).

Natural gas
is a nonrenewable energy source formed by a gas mixture that is commonly found in oil fields, non-partner (single), dissolved or associated with the (accompanying) oil or coal deposits. Although its composition varies depending on the site of which is extracted, is mainly composed of methane in quantities that can commonly exceed 90 or 95% (eg., Non-associated gas from the well West Sole in the North Sea) , and usually contains other gases such as nitrogen, CO 2, H 2 S, mercaptans and helium. Examples of contaminants include non-associated gas from Kapuni (NZ) containing up to 49% CO 2. As additional sources of this natural resource, is investigating the methane hydrate deposits, according to estimates, could pose a much greater energy reserves to current natural gas.
It may also be obtained by processes of decomposition of organic debris (garbage, plants - marsh gas) in the treatment plants of these remains (urban waste water treatment plants, garbage processing plants, of alpechines, etc.).. The gas thus obtained is called biogas.
Generation of CO 2 in comparison with other gases
Natural gas produces much less CO2 than other fuels such as oil and especially coal. It is also a fuel that burns more cleanly and efficiently.
The reason produces little CO 2 is that the main component, methane, contains four atoms of hydrogen and carbon, producing 2 molecules of water for each of CO 2, while long-chain hydrocarbons (liquid) yield only 1 molecule of water per 1 CO 2 (remember that the heat of formation of water is very high).
As an added benefit is a more versatile fuel, which can be used in generation systems more efficient as combined cycle or fuel cell and its acquisition is easier compared to other fuels. However, its energy content per unit volume is low compared to other fuels.

Liquid Natural Gas LNG = LPG + NG
The natural gas liquids (NGL), consisting of ethane, propane, butane and other heavier hydrocarbon components are used in the domestic market as fuel and raw material (including petrochemicals).
To convert natural gas into liquid, it cools the treated gas to about -161 ° C, which is the temperature at which methane-the main component, becomes a liquid. The liquefaction process of cooling is similar to common refrigerant gases are compressed to produce cold liquids such as propane, ethane / ethylene, methane, nitrogen or mixtures thereof, which then evaporates as heat exchange with the gas stream natural. Thus, natural gas is cooled to the point where it becomes liquid. Once the liquefied gas has been subjected to a process of Joule Thompson expansion or extraction work so that it can be stored at atmospheric pressure. The LNG produced is stored in special tanks and are then transferred to special transport tankers.
The natural gas extracted from the deposits, a product is colorless, odorless, nontoxic and lighter than air. From the decomposition of organic matter sediments trapped between rock layers and is a mixture of light hydrocarbons in which methane (CH4) is found in large proportions, together with other oil and gas whose concentration depends on the location of the site.

LPG or Autogas.

LPG consists mainly of butane and propane, and you get both natural gas and the process of refining of oil and gas is available in large quantities throughout the world, so in principle not easily be exhausted .

Its main advantage is that any petrol car can, with a slight modification, use it, thereafter becomes bi-fuel and can move with either fuel.
»Corruption for the user, for its lower cost of production, natural gas will always be cheaper than traditional fuels. This economy is not only for its price but by the savings in vehicle maintenance costs as it increases the life of certain items such as spark plugs, exhaust system, carburetor, as well as the lubricant.
· Transportation and distribution infrastructure Harnessing existing gas lines, industrial and domestic natural gas networks, as well as existing service stations gasoline, which can become mixed gasoline outlets / GNV.
· Reliability of the product supply to the delta of NGV is much safer and reliable than other automotive fuels, since receiving the product is made directly through the gas networks and not trucks. Moreover, the product features make it difficult to alter.
Additional Income · foreign exchange for the nation is generating additional foreign exchange earnings, export product of the volumes of liquid hydrocarbons released into the domestic market.
• Test weight / volume of cylinders; The gas storage cylinder, means additional weight and space, which translates to a reduction of vehicle load, this being particularly critical for small cars, this disadvantage does not exist for commercial vehicles ( minibuses, buses, pickup, trucks etc) as these can support the weight of the tanks and also have more space available to place storage cylinders.
Loss of acceleration; Due to its characteristics, natural gas produces a power loss on the vehicle of approximately 15%, which becomes more obvious on the stage of removal of material on vehicles with low engine displacement.
For their properties, the NGV is a safer fuel than traditional ones because it is lighter than air and dissipates quickly, while the gasoline vapors are 5 times heavier and therefore can accumulate in low places ventilated, creating potentially explosive mixtures.
The training range is wider explosive mixtures in gasoline in the NGV. The lower flammable limit is lower in gasoline when compared to the NGV, which means it's more likely the formation of flammable air-fuel mixtures that Air-GNV. Moreover, the NGV requires higher temperature than gasoline for ignition in the air.

Entradas relacionadas: