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What is Combustion? Fire is a chemical chain reaction which takes place with the evolution of heat and light. In order for a fire to take place there are 3 main ingredients that must be present: Oxygen, Heat and Fuel. In chemistry we call the type of reaction that produces fire a combustion reaction.
Combustion is a high-temperature exothermic heat releasing redox oxygen adding chemical reaction between a fuel and an oxidant, usually atmospheric oxygen, that produces oxidized, often gaseous products, in a mixture termed as smoke.
Whenever we complete a combustion reaction a hydrocarbon compound of C and H there are generally the same products formed: CO 2 and H 2 O. The fuel you burn in your car's engine contains octane, C 8 H In order to better understand the energy changes taking place during a reaction, we need to define two parts of the universe, called the system and the surroundings.
The system is the specific portion of matter in a given space that is being studied during an experiment or an observation. The surroundings is everything in the universe that is not part of the system. In practical terms for a laboratory chemist, the system is the particular chemicals being reacted, while the surroundings is the immediate vicinity within the room.
During most processes, energy is exchanged between the system and the surroundings. If the system loses a certain amount of energy, that same amount of energy is gained by the surroundings. If the system gains a certain amount of energy, that energy is supplied by the surroundings. In the study of thermochemical processes, things are viewed from the point of view of the system.
A chemical reaction or physical change is endothermic if heat is absorbed by the system from the surroundings. In the course of an endothermic process, the system gains heat from the surroundings and so the temperature of the surroundings decreases. The quantity of heat for a process is represented by the letter. The sign of for an endothermic process is positive because the system is gaining heat.
A chemical reaction or physical change is exothermic if heat is released by the system into the surroundings. Because the surroundings is gaining heat from the system, the temperature of the surroundings increases. The sign of for an exothermic process is negative because the system is losing heat.
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