FREE ESSAY ON COMBUSTION & CARBON DIOXIDE

COMBUSTION & CARBON DIOXIDE

COMBUSTIOn & carbon Dioxide
Research
By Rabon Hutcherson II.
Combustion and carbon dioxide, what are they? When people think of combustion they
probably think of simple just bursting into flames; and for carbon dioxide you probably
think of what we breath out and what plants take from the air and turn to oxygen. Even
though these thoughts are true there is much more to combustion and carbon dioxide.
Things you might not think of about combustion are, mathematical equations, models,
solutions and chemical reactions, and for carbon dioxide dry ice, combustion and it being
a solid. All of these factors you may not have known are now here for you to see.
One of the things that has lead the way for the study of combustion is the Combustion
Theory. Combustion Theory is the use of theoretical methods (mathematics, modeling,
numerics, etc. in the study of combustion phenomena. Although Faraday and others in the
middle of the 19th century and around beginning of the 20th century laid some early
foundations, it was not until the middle of the 20th Century that von Karman and a
Russian School, involving Frank-Kamenetskii and Zeldovich, prepared a sound basis for the
theory. Von Kerman referred to this as aerothermochemistry, in which every imaginable
physical transport, chemical and thermodynamic process is thrown into the melting pot - a
vast field of developing knowledge in Physics, Chemistry, Engineering and Mathematics.
The development of systematic asymptotic techniques in Caltech during the 1960s opened
the way towards revealing an underlying simplicity in many combustion processes,
involving fairly simple mathematical models and solutions. Computers have also made it
possible to treat many problems in their fuller, more complicated form. It can also be
stated that Combustion Theory has provided a rich range of equations with fascinating
mathematical properties. These include the Sivashinsky equation which approximates the
destabilizing effect of density change in flames; the Kuramoto-Sivashinsky equation which
approximates an anti-diffusive destabilizing effect that some flames possess; and
Clarke's equation which describes chemical and pressure-wave interactions in a detonable
chemical mixture. These equations, and some milestone solutions and dimensionless numbers
that have helped to punctuate the growth of this field of research can be spotted in the
following artistic impression of Combustion Theory". The three fundamentals for
combustion are fire, fuel and heat. Fire is a chemical reaction involving rapid oxidation
or burning of a fuel. It needs three elements to occur, fuel can be any combustible
material - solid, liquid or gas. Most solids and liquids become a vapor or gas before
they will burn. The air we breathe is about 21 percent oxygen. Fire only needs an
atmosphere with at least 16 percent oxygen. Heat is the energy necessary to increase the
temperature of the fuel to a point where sufficient vapors are given off for ignition to
occur. Heat of combustion, heat released during combustion. In particular, it is the
amount of heat released when a given amount (usually 1 mole) of a combustible pure
substance is burned to form incombustible products (e.g., water and carbon dioxide); this
amount of heat is a characteristic of the substance. Heats of combustion are used as a
basis for comparing the heating value of fuels, since the fuel that produces the greater
amount of heat for a given cost is the more economic. Heats of combustion are also used
in comparing the stabilities of chemical compounds. For example, if equal quantities of
two isomeric hydrocarbons burn to produce equal amounts of carbon dioxide and water, the
one releasing more energy is less stable, since it was the more energetic in its
compounded form. Certain combustible metals, such as magnesium, titanium, potassium and
sodium burn at high temperatures and give off sufficient oxygen to support combustion.
They may react violently with water or other chemicals, and must be handled with care.
Combustion, rapid chemical reaction of two or more substances with a characteristic
liberation of heat and light; it is commonly called burning. The burning of a fuel (e.g.,
wood, coal, oil, or natural gas) in air is a familiar example of combustion. Combustion
need not involve oxygen; e.g., hydrogen burns in chlorine to form hydrogen chloride with
the liberation of heat and light characteristic of combustion. Combustion reactions
involve oxidation and reduction. Before a substance will burn it must be heated to its
ignition point, or kindling temperature. Pure substances have characteristic ignition
points. Although the ignition point of a substance is essentially constant, the time
needed for burning to begin depends on such factors as the form of the substance and the
amount of oxygen in the air. A finely divided substance is more readily ignited than a
massive one; e.g., sawdust ignites more rapidly than does a log. The vapors of a volatile
fuel such as gasoline are more readily ignited than is the fuel itself. The rate of
combustion is also affected by these factors, particularly by the amount of oxygen in the
air. The nature of combustion was not always clearly understood. The ancient Greeks
believed fire to be a basic element of the universe. It was not until 1774 that the
French chemist A. L. Lavoisier performed experiments that led to the modern understanding
of the nature of combustion. Spontaneous combustion, phenomenon is when a substance
unexpectedly bursts into flame without apparent cause. In ordinary combustion, a
substance is deliberately heated to its ignition point to make it burn. The most famous
cases of spontaneous combustion is the mysterious phenomenon of human combustion. This is
when a person just starts to burn; they don't have to burst into flames they could just
simple smoke are burn internally outward. This is a very true event, but also very rare.

Joseph Black, a Scottish chemist and physician, first identified carbon dioxide in the
1750s; carbon dioxide is a colorless, odorless gas. It occurs in the atmospheres of many
planets, including that of the earth. On the earth, all green plants must absorb carbon
dioxide from the atmosphere to live and grow. Green plants convert carbon dioxide and
water into food and oxygen. Plants and animals, in turn, burn the food by combining it
with oxygen to release energy for growth and other life activities. This process, called
respiration is the reverse of photosynthesis. Oxygen is used up and carbon dioxide and
water are used to produce more food and oxygen. The cycle of photosynthesis and
respiration maintains the earth's natural balance of carbon dioxide and oxygen. Carbon
dioxide is essential in the role of internal respiration. Internal respiration refers to
the process by which oxygen is transported to body tissues and carbon dioxide is carried
away from them. This carbon dioxide is also a chief guardian of the pH of the blood,
which is essential for survival. This buffer system - called the carbonate buffer - is
made up of bicarbonate ion and dissolved carbon dioxide plus carbonic acid. The carbonic
acid can neutralize hydroxide ions which if added, would increase the pH of the blood and
cause alkalosis. The bicarbonate ion can neutralize hydrogen ions that, if added, would
cause a decrease in the pH of the blood and lead to acidosis. Both changes in pH are life
threatening. The carbon dioxide in the earth's atmosphere helps regulate the planet's
temperature. When sunlight reaches the earth, some of it is converted into heat. The
carbon dioxide absorbs some of the heat and so helps keep it near the earth's surface. If
all the heat from the sunlight escaped into outer space, the earth would become very
cold. The amount of carbon dioxide in the atmosphere has been increasing since about
1890, chiefly as a result of the burning of fuels that contain carbon. This increase has
caused a slight rise in the earth's average temperature. Carbon dioxide has important
uses in the home and in industry. For example, carbon dioxide released by baking powder
or yeast makes cake batter rise. Carbon dioxide in soft drinks, beer, and sparkling wines
gives the beverages their fizz. Some fire extinguishers use carbon dioxide because it
does not bum and because pure carbon dioxide is denser than air. Carbon dioxide's
heaviness enables it to blanket a fire and prevent oxygen from getting to the fire thus
starving the burning material of the oxygen it needs to continue burning. Dry ice is
solid carbon dioxide. Carbon dioxide becomes a solid at -78.5 0C. The name dry ice refers
to the fact that the substance changes from a solid to a gas without first becoming a
liquid. Because of this property, dry ice is widely used in industry to refrigerate food,
medicine, and other materials that would be damaged by the melting of ordinary ice.
Carbon dioxide is one of the most important compounds on earth. Its importance to
industry and the survival of all life are well documented. Without it, all human life
would cease to exist. We all owe a debt of gratitude to our friend CO2 of burning,
releases heat. If the heat so released cannot escape the substance, the temperature of
the substance rises until ignition takes place. Spontaneous combustion often occurs in
piles of oily rags, green hay, leaves, or coal; it can constitute a serious fire hazard.
Carbon dioxide CO2, chemical compound, occurs as a colorless, odorless, tasteless gas
that is about 1 1/2 times as dense as air under ordinary conditions. It does not burn and
will not support combustion of ordinary materials. Its weakly acidic aqueous solution is
called carbonic acid. The gas, easily liquefied by compression and cooling, provides the
sparkle in carbonated beverages. Solid carbon dioxide, or dry ice, is a refrigerant.
Dough rises because of carbon dioxide formed by the action of yeast or baking powder.
Carbon dioxide is a raw material for photosynthesis in green plants, and is a product of
animal respiration and of the decay of organic matter. Carbon dioxide occurs both free
and combined in nature, and makes up about 1% of the volume of dry air. It can cause
death by suffocation if inhaled in large amounts. Carbon dioxide is a gas that occurs in
the atmosphere and is produced in body tissues as a waste product of energy-generating
processes. Dissolved in the blood, carbon dioxide is carried to the lungs, and from there
it is exhaled as a gas. Some carbon dioxide also leaves the body in urine and in
perspiration. If the level of carbon dioxide in the blood rises above normal, the brain
automatically stimulates the lungs into working faster. The increase in breathing rate is
necessary to rid the body of the extra carbon dioxide, but it may be harmful in other
ways. CO2, a colorless gas having a faint, sharp odor and a sour taste; it is a minor
component of the Earth's atmosphere (about 3 volumes in 10,000), formed in combustion of
carbon-containing materials, in fermentation, and in respiration of animals and employed
by plants in the photosynthesis of carbohydrates. The presence of the gas in the
atmosphere keeps some of the radiant energy received by the Earth from being returned to
space, thus producing the so-called greenhouse effect. Industrially, it is recovered for
numerous diverse applications from flue gases, as a by-product of the preparation of
hydrogen for synthesis of ammonia, from limekilns, and from other sources. Carbon dioxide
was recognized as a gas different from others early in the 17th century by a Belgian
chemist, Jan Baptist van Helmont, who observed it as a product of both fermentation and
combustion. By the mid-20th century, most carbon dioxide was sold as the liquid. If the
liquid is allowed to expand to atmospheric pressure, it cools and partially freezes to a
snow like solid called Dry Ice that sublimes (passes directly into vapor without melting)
at -78.5? C (-109.3? F) at the pressure of the normal atmosphere. At ordinary
temperatures, carbon dioxide is quite unreactive; above 1,700? C (3,100? F) it partially
decomposes into carbon monoxide and oxygen. Hydrogen or carbon also converts it to carbon
monoxide at high temperatures. Ammonia reacts with carbon dioxide under pressure to form
ammonium carbonate, then urea, an important component of fertilizers and plastics. Carbon
dioxide is slightly soluble in water (1.79 volumes per volume at 0? C and atmospheric
pressure, larger amounts at higher pressures), forming a weakly acidic solution. This
solution contains the dibasic acid called carbonic acid (H2CO3). Carbon dioxide is used
as a refrigerant, in fire extinguishers, for inflating life rafts and life jackets,
blasting coal, foaming rubber and plastics, promoting the growth of plants in
greenhouses, immobilizing animals before slaughter, and in carbonated beverages. Ignited
magnesium continues to burn in carbon dioxide, but the gas does not support the
combustion of most materials. Prolonged exposure of humans to concentrations of 5 percent
carbon dioxide may cause unconsciousness and death.
Bibliography
Combustion & Carbon dioxide
Bibliography
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