Reaction rate The rate of a reaction is defined in terms of the rates with which the products are formed and the reactants the reacting substances are consumed. For chemical systems it is usual to deal with the concentrations of substances, which is defined as the amount of substance per unit volume. The rate can then be defined as the concentration of a substance that is consumed or produced in unit time.
It so happens that combustion is a particularly dramatic type of oxidation-reduction reaction: Even more dramatic is combustion that takes place at a rate so rapid that it results in an explosion.
Coal is almost pure carbon, and its combustion in air is a textbook example of oxidation-reduction. Although there is far more nitrogen than oxygen in air which is a mixture rather than a compoundnitrogen is very unreactive at low temperatures.
For this reason, it can be used to clean empty fuel tanks, a situation in which the presence of pure oxygen is extremely dangerous. In any case, when a substance burns, it is reacting with the oxygen in air.
As one might expect from what has already been said about oxidation-reduction, the oxygen is reduced while the carbon is oxidized. Combustion has been a significant part of human life ever since our prehistoric ancestors learned how to harness the power of fire to cook food and light their caves.
In fact, our modern age is even more combustion-driven than that of our forebears. For centuries, burning animal fat—in torches, lamps, and eventually in candles—provided light for humans.
Wood fires supplied warmth, as well as a means to cook meals. These were the main uses of combustion, aside from the occasional use of fire in warfare or for other purposes including that ghastly medieval form of execution, burning at the stake. One notable military application, incidentally, was "Greek fire," created by the Byzantines in the seventh century A.
A mixture of petroleum, potassium nitrate, and possibly quicklime, Greek fire could burn on water, and was used in naval battles to destroy enemy ships. For the most part, however, the range of activities to which combustion could be applied was fairly narrow until the development of the steam engine in the period from the late seventeenth century to the early nineteenth century.
The steam engine applied the combustion of coal to the production of heat for boiling water, which in turn provided the power to run machinery. By the beginning of the twentieth century, combustion had found a new application in the internal combustion engine, used to power automobiles.
An internal combustion engine does not simply burn fuel; rather, by the combined action of the fuel injectors in a modern vehiclein concert with the pistons, cylinders, and spark plugs, it actually produces small explosions in the molecules of gasoline.
These produce the output of power necessary to turn the crankshaft, and ultimately the wheels. An explosion, in simple terms, is a sped-up form of combustion. The first explosives were invented by the Chinese during the Middle Ages, and these included not only fireworks and explosive rockets, but gunpowder.
Ironically, however, China rejected the use of gunpowder in warfare for many centuries, while Europeans took to it with enthusiasm. Needless to say, Europeans' possession of firearms aided their conquest of the Americas, as well as much of Africa, Asia, and the Pacific, during the period from about to The late nineteenth and early twentieth centuries saw the development of new explosives, such as TNT or trinitrotoluene, a hydrocarbon.
Then in the mid-twentieth century came the most fearsome explosive of all: A nuclear explosion is not itself the result of an oxidation-reduction reaction, but of something much more complex—either the splitting of atoms fission or the forcing together of atomic nuclei fusion.
Nuclear bombs release far more energy than any ordinary explosive, but the resulting blast also causes plenty of ordinary combustion.
Japanese cities of Hiroshima and Nagasaki in Augustthose cities suffered not only the effects of the immediate blast, but also massive fires resulting from the explosion itself.
Oxidation-reduction reactions also fuel the most advanced form of transportationknown today, the space shuttle. The actual orbiter vehicle is relatively small compared to its external power apparatus, which consists of two solid rocket boosters on either side, along with an external fuel tank.
Inside the solid rocket boosters are ammonium perchlorate NH 4 ClO 4 and powdered aluminum, which undergo an oxidation-reduction reaction that gives the shuttle enormous amounts of extra thrust.
As for the larger single external fuel tank, this contains the gases that power the rocket: Because these two are extremely explosive, they must be kept in separate compartments.
When they react, they form water, of course, but in doing so, they also release vast quantities of energy. The chemical equation for this is: On January 28,something went terribly wrong with this arrangement on the space shuttle Challenger. Cold weather had fatigued the O-rings that sealed the hydrogen and oxygen compartments, and the gases fed straight into the flames behind the shuttle itself.
This produced a powerful and uncontrolled oxidation-reduction reaction, an explosion that took the lives of all seven astronauts aboard the shuttle.
The Environment and Human Health Combustion, though it can do much good, can also do much harm. This goes beyond the obvious: In fact, oxidation-reduction reactions are intimately connected with the functioning of the natural environment.
For example, photosynthesis, the conversion of light to chemical energy by plants, is a form of oxidation-reduction reaction that produces two essentials of human life: Likewise cellular respiration, which along with photosynthesis is discussed in the Carbon essay, is an oxidation-reduction reaction in which living things break down molecules of food to produce energy, carbon dioxide, and water.
Enzymes in the human body regulate oxidation-reduction reactions.The balanced equation for photosynthesis is: 6CO2 + 6H2O + sunlight energy = C6H12O6 + 6O2 Photosynthesis can be represented using a chemical equation: Carbon dioxide + water + light energy gives a carbohydrate + oxygen.
The formula for photosynthesis is 6CO2 + 6H2O + light energy = C6H12O6 + 6O2. In words, the equation translates to the combining of water, carbon dioxide and light energy to produce glucose and oxygen.
CHEMISTRY JOURNALS ACS, RSC, etc. Journals. ACS PUBLICATIONS - American Chemical Society Multimedia American Chemical Society Journals & Magazines (Text & Images).
For more information see the American Chemical Society Examples from over "30" Online ACS Magazines & Journals include. The most general chemical equation for oxygen based photosynthesis is as follows: CO2 + H2O + photons --> CH2O + O2.
This can be read as carbon dioxide plus water plus photons (energy from. BioCoach Activity Photosynthesis Introduction. Photosynthesis is a process by which light energy is converted into chemical energy. Understanding energy conversions is not trivial, and this BioCoach activity is designed to enhance your understanding and retention of the content by illustrating and animating the fundamental processes involved in photosynthesis.
Exposing the climate geoengineering cover-up.
Though the official ozone layer “recovery” lie is still being propagated, some sources are acknowledging reality as the truth becomes ever more difficult to hide.. Much more geoengineering / ozone destruction supporting data is listed below.