Rates of Reaction

Rates of Reaction

The rate of a reaction measures how quickly reactants are used up or products are formed. Several factors can speed a reaction up.

Factors that increase rate

Higher temperature, higher concentration (or pressure for gases), and a larger surface area of solid reactants all increase the rate of reaction by increasing how often particles collide, how energetically they collide, or both. Adding a catalyst works differently: it provides an alternative reaction pathway with a lower activation energy, so a greater proportion of collisions are successful — without increasing how often particles collide.

Collision theory

For a reaction to happen, particles must collide with enough energy (called activation energy) and in the right orientation. Anything that increases the frequency or energy of successful collisions speeds up the reaction.

Practice

Why does crushing a solid into powder make it react faster than in one large lump?