Note that the mean energy of the particles does not change. However, since the frequency of collisions increases, the frequency of successful collisions also increases.
The gradient of the line is equal to the rate of reaction. The faster reaction with the powder:
Icing sugar is made from a fine powder, whereas granulated sugar is made from much larger crystals. State and explain which will burn more quickly in air.
Icing sugar will burn in air more quickly than granulated sugar because it has a much larger surface area to volume ratio than granulated sugar. This means that successful collisions with the oxygen molecules in the air will be more frequent.