蜜芽传媒

Demonstrations with charcoal, gunpowder and steel wool show the effect of particle size and concentration on chemical reaction rates. Charcoal burns slowly in air as oxygen can only reach the outside of the lump. Blowing on the charcoal increases the oxygen supply and speeds up the reaction. Gunpowder contains both charcoal and chemicals containing oxygen in small particles. The reaction is therefore much quicker. Similarly, steel wool burns quickly as the oxygen can reach a large surface area.