The charcoal powder burns faster than the piece of charcoal.Why ?
Answers
Hey Combustion requires three things; fuel, oxygen and a source of ignition. The oxygen needs to be in contact with the fuel to cause combustion, because combustion of solids is a surface phenomenon. Not only must the oxygen be in contact with the surface of the solid piece, but any solid combustion products, such as ash need to fall away to expose fresh fuel for further combustion to take place. Large pieces of fuel have a much smaller surface area than the equivalent weight of smaller pieces. And the smaller you go, the larger the surface area exposed to oxygen becomes. A powder can have hundreds of times the surface area of an equal weight of the same substance in block form. This means that if the powdered fuel is suspended in air and and ignition source is applied, the fuel cloud can burn so fast that it literally explodes. Such explosions are called “combustible dust explosion" and may occur anywhere where a flammable dust cloud could be formed. For example in coal mines, grain silos, flour mills, or any facility capable of producing a combustible dust. So in summary, finely-divided solid fuels burn faster than larger pieces because oxygen reacts faster with a larger surface area of fuel.