Final answer:
Fires resulting from ordinary combustibles like wood and paper are classified as Class A. These combustibles require a sufficient heat source to overcome the activation energy for ignition, after which they can sustain a fire. Understanding this helps with fire safety and managing combustion pollutants.
Step-by-step explanation:
Fires that result from ordinary combustibles, such as wood and paper, are Class A.
This classification is part of a system used to categorize different types of fires based upon the fuels involved, which in turn dictates the best methods for extinguishing them.
Ordinary combustibles like wood and paper are common materials that can ignite and sustain a fire; these are organic materials that combust with the chemically bonded oxygen within their molecular structure.
Combustion reactions, like those that occur in Class A fires, involve the rapid chemical combination of a substance with oxygen to produce oxides and release heat.
The temperature of a burning material such as wood is an intensive property, meaning that the temperature of 1 gram of wood will be the same whether it is in a match or a bonfire.
However, the total heat released is an extensive property, depending on the amount of material present.
Therefore, even though the temperature of a piece of wood in a bonfire is the same as that in a match, the bonfire produces a significantly larger amount of heat due to the larger quantity of wood.