What is the difference between burning something fast or slow?

Question

Because they both put out the same amout of energy.

Answer 1

When burning something fast there are more chances that there is not a lot of oxygen present at the reaction and thus you get products of incomplete combustion.
E.g. full combustion of an organic compound gives carbon dioxide and other products, while incomplete gives a mixture of carbon monoxide and dioxide.

Answer 2

An object that burns quickly is an explosive. An object that burns slowly is said to be deflagerating. Enjoy Wikipedia!

"Damage to buildings, equipment and people can result from a large-scale short-duration deflagration. The nature of the damage is primarily a function of the total amount of fuel burned in the event (total energy available), the maximum flame velocity that is achieved, and the manner in which the expansion of the combustion gases is contained.

In free-air deflagrations, there is a continuous variation in deflagration effects relative to maximum flame velocity. When flame velocities are low, the effect of a deflagration is the release of heat. Some authors use the term flash fire to describe these low-speed deflagrations. At flame velocities near the speed of sound, the energy released is in the form of pressure and the results resemble a detonation. Between these extremes both heat and pressure are released.

When a low-speed deflagration occurs within a closed vessel or structure, pressure effects can produce damage due to expansion of gases, as a secondary effect. The heat released by the deflagration causes the combustion gases and excess air to try to expand thermally as well. The net result is that the volume of the vessel or structure needs to either expand/fail to accommodate the hot combustion gases, or build internal pressure to contain them."

"An explosion is a sudden increase in volume and release of energy in a violent manner, usually with the generation of high temperatures and the release of gases. An explosion causes pressure waves in the local medium in which it occurs. Explosions are categorized as deflagrations if these waves are subsonic and detonations if they are supersonic (shock waves)."

Answer 3

Assuming the fuel in question is completey burned then the amount of energy output is the same regardless of the 'speed' at which it burns. If it burns for less time (faster) then it is hotter as the energy comes out quickly. If it burn over a greater amount of time (slower) then it burns colder as the energy comes out slowly. The best analogy I can think of is the fact that the ocean contains more heat energy than a cup of boiling water.

Answer 4

The process is very important, as well as the degree of burnt material! The efficiency of burning is very important. We might burn something slow but ineffectively, or fast and effectively!
Also, the set up is important and how e utilize the resulting products and energy. From the data you are giving with your question I can not give an adequate answer.

Answer 5

Then again, you can force more oxygen in to get a faster more complete burn... that's what turbochargers do on cars and if you have ever seen a blacksmith working a bellows... it makes a hotter fire than if it was burning slower, and you can get more work out of it.