Ignition point of dust
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Does the ignition point of combustible dusts decrease as their particle size gets smaller? For example, sulfur burns very slowly in its solid form, but it burns extremely rapidly once it becomes dust; I’m not sure why
When combustible solids are turned into dust, their surface area increases. For example, when sulfur is converted to powder, its surface area increases by many times, which means it has many more opportunities to come into contact with oxygen, thereby increasing its reactivity. This seems to be a problem related to physical chemistry; unfortunately, I already gave it to my teacher.
Well, are there any similar guidelines or explanations? I’m wondering whether the ignition point decreases when the specific surface area increases, and what the trend is
An increase in specific surface area does not lower the ignition point; however, the time it takes for the initial temperature to reach the ignition point is **reduced**, and the combustion becomes more intense.
The reason is simple: it increases the surface area in contact with oxygen. To give a simple example, consider cooking over firewood in rural areas. If too much firewood is piled up and it’s too dense, it’s difficult to ignite the fire; but if the firewood is arranged so that there’s more oxygen around it, the fire will catch quickly.
Agree with the person above; once the type of material is determined, its ignition point is also fixed, and it cannot change due to differences in size or shape.