Question

Based on your knowledge of factors affecting the rate of reaction, why is there a danger of explosions in places such as flour mills and coal mines where there are large quantities of powdered, combustible materials? 

Answer 1

The large quantities of powdered, combustible materials in silos and coal mines would equate to a higher concentration of materials and technically, a higher surface area. Coincidentally, these places often harbor higher temperatures, increasing the collision frequency. With these three factors combined, there would be an increased reaction rate and this case, a quicker rate for the combustible materials to be released in the form explosions.