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Fire Phenomena
Q. What is fire?
Fire is a chemical oxidation reaction between fuel (combustibles) and
oxidizing chemicals (like oxygen). This process is also known as
combustion, characterized by a rapid, persistent chemical change that
releases heat and light and is accompanied by visible flames. The heat
produced by the fire accelerates the combustion process.
Q. When
did human beings discover oxygen?
In trying to figure out fire, human beings discovered
something even more fundamental: oxygen. They found out that if the
oxygen level was low enough, a fire could not exist, and may even be
suppressed by lowering the oxygen in a fire zone. Artist and inventor
Leonardo da Vinci was among the first to note that a flame goes out
without air, like a living being suffocates. The oxygen was identified
as the "living source" necessary to humans and also to
combustion processes.
Q. What
happens to oxygen in a fire?
It is sucked into all burning materials, reacting with the
combustible chemicals (like hydrocarbons) to produce mainly water vapor
and carbon dioxide. Also in combustion processes involving oxygen and
metals it was found that weight was added to the heated metals and a
thin layer of metal oxides was produced. This oxide was evidence to the
oxygen participation in the metal oxidation process.
Q. What is
oxidation?
Basically this is a chemical reaction that occurs when a
substance is exposed to oxygen. The oxygen reacts with elements in the
substance to change it and produces various decomposition products. If a
fuel (such as wood) is heated while exposed to oxygen, the oxygen will
bond much more quickly to the fuel's hydrogen and carbon atoms to
produce water vapor and carbon oxides.
Q. What is exothermic
oxidation?
This is a chemical reaction that produces heat energy. Fire
is a typical exothermic reaction that produces heat radiation (elevated
temperatures) as well as optical radiation (visible and invisible
light).
Q. What
are the properties of wood that cause it to burn?
Wood is based on a chemical substance known as cellulose.
This substance is of organic origin, produced when oxygen atoms combine,
over time, with carbon and hydrogen atoms in a "hydrocarbon"
like material. The wood is flammable, and given the right conditions
(elevated temperatures and oxygen presence), burns.
Q. Where
does oxidation occur?
From the fast burning of a wood fire's leaping flames, to
the much slower, more controlled "burning" of food inside the
body, oxidation goes on continuously all around us.
Q. Is
fire a solid, a liquid or a gas?
The fire or combustion process takes place in the gaseous
phase although the fuel that burns in a fire can be a chunk of wood or
lump of coal solid or gasoline or kerosene liquid or natural gas or
propane (gas). All flammable materials decompose upon exposure to heat
and most of the combustion processes take place in the gaseous phase.
Q. What
is the ignition point?
The minimum temperature at which a substance will continue
to burn without additional application of external heat.
Q. When
does the chemical reaction reach an ignition point?
The oxidation process can accelerate to the ignition point
when the energy produced in the combustion process is emitted as heat
that can be felt and seen (as light).
Q. What
is a cause for a flame to extinguish independently?
A flame goes out without air (oxygen), like a living being
suffocates.
Q. Where
does one experience the unique phenomena of a substance on fire without
producing a flame?
According to scientists, a red-hot coal is an object that
can even be on fire without producing a visible flame. Smoldering fires
burn without visible flames.
Q. What is a flame?
The flame is the visible part of a fire process. It is a
collection of hot gases, including carbon dioxide and steam, rising from
a burning material as a hot, glowing mass visible as brightly colored,
flickering light.The flame radiates ultraviolet, visible and infrared
energy (optical spectrum) that can be detected by optical detectors.
Q. What is soot?
Glowing embers rising into the air from a flame are solid
particles called soot. These are fine black particles, chiefly composed
of carbon, produced by incomplete combustion of coal, oil, wood, or
other fuels.
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