Question

Explain the following:

One gram of pulverised wood burns faster than a one gram piece of wood.

Answer 1

When one gram of wood is in the form of pulverised (powdered) particles, its surface area is much larger compared to a single solid piece of wood of the same mass.

1. Burning of wood is a chemical reaction between carbon-containing compounds in the wood and oxygen from the air.
2. The reaction takes place only at the surface where oxygen can come in contact with the wood.
3. Pulverising the wood breaks it into many tiny particles, increasing the total surface area exposed to oxygen.
4. With more contact area, more oxygen molecules can react simultaneously, increasing the overall reaction rate.
5. A finely powdered sample burns faster than a lump of the same mass because a larger surface area increases the rate of the reaction.