Factors effecting the rate of a reaction:
Temperature (increase):
- particles gain kinetic energy
- particles collide more often and more frequently with energy more than activation energy
- so more frequent successful collisions happen
- rate of reaction is increased.
Concentration of the reactant particles (increase):
- there are more particles per unit area
- collisions between particles happen more frequently
- more successful collisions between reactant particles
- rate of reaction is increased
Note: particles do not gain energy when concentration is increased unlike in temperature
Concentration of non-reactant particles (increase):
- adding a non-reactant decreases the concentration (particles per unit area) of the reactant particles and they end up getting apart.
- as particles increased, collisions between particles overall increases, but a successful collision is needed for the reaction to happen, which is a collision
between reactant particles, now as their concentration has decreased, they collide less so even though collisions have increased, successful collisions have
decreased
- so this decreases rate of reaction
Pressure of a gas reactant (increase):
- increasing the pressure of a gas makes them collide more.
- as collisions are more, the rate of successful collsions (collisions between reactant particles) increases as a result
- the rate of reaction is increased.
Surface area of solid reactant (increase):
- more surface area means more exposure to the other reactant particles
- as a result of higher exposure, there are more collisions between reactant particles
- increasing the successful collisions
- rate of reaction is increased
Inorganic catalyst:
- A catalyst speeds up the rate of reaction without being used up or altered itself
- so rate of reaction increases, but the catalyst remains unsed and can be used for a new batch of the same reaction.
Note: Inorganic catalysts, are not made from organic material, transition metals and their compounds usually act as inorganic catalysts. They are not
temperature sensitive, however, some catalysts such as V2O5 [Vanadium (V) oxide] are inactive below a certain temperature.
Organic catalyst (enzymes):
- Organic catalysts, such as enzymes are biological catalysts that speed up the rate of reaction without being used up or altered themselves.
- They are highly temperature and pH sensitive
- They are inactive or less active at temperatures below their optimum temperature
- They denature/get destroyed at high temperatures more than their optimum temperature
- They are the most active at their optimum temperature, giving the highest rate of reaction at that temperature.
Surface area of catalyst in a reaction with gas reactants (increase):
- If the reactants in a reaction are gases, the catalyst's surface area can determine the rate of reaction too.
- With greater surface area of catalyst, the gas reactants get more exposed to it.
- with more exposure, more successful collisions (collisions between gas reactant particles) can be catalysed.
- so rate of reaction increases
By Rafay Saqib