Increasing the concentration of a solution increases the collision rate.
This is because there will be more reactant particles per unit volume, causing more frequent collisions so there are more successful collisions per second, increasing the rate of reaction.
Extended for IGCSE and a better understanding:
Increasing the concentration means there are more particles per cm3, so there is less space between the particles
Since there are more particles then it follows that there are more frequent collisions, increasing colllision rate and so the rate of the reaction increases
@@Increasing the temperature increases the rate of reaction@@
This is because the particles will have more energy and move faster, therefore there will be a greater collision rate
Also, a higher proportion of particles will have greater than the required activation energy, and therefore have sufficient energy to react, meaning there will be more successful collisions per second, increasing the reaction rate
Extended for IGCSE and a better understanding:
@@Particles need to have sufficient energy to react when they collide@@
@@This is called the activation energy@@
@@At low temperatures only a small number of particles will have the required activation energy so the reaction will be slow@@
@@At higher temperatures the particles have more kinetic energy so they move faster and with more energy@@
@@The collisions are therefore more energetic, and there are then a greater number of particles with sufficient energy to react, so the rate of reaction increases@@
Increasing the surface area of a solid increases the collision rate
This is because more of the solid particles will be exposed to the other reactant so there will be more frequent collisions and therefore more successful collisions per second, increasing the rate of reaction
Catalysts (including enzymes) create alternative reaction pathways which have a lower activation energy
This means that more collisions will have sufficient energy to be successful
When a catalyst is used, the rate of reaction will increase
As you’ve seen you can increase the rate of reaction by increasing the concentration, temperature and the surface area of solid reactant.
In some situation an increase in any of these can lead to a dangerously fast reaction. you can get an Explosion .
Explosive combustion occurs when there are many fine particles in the air
Many industrial processes such as metal working, coal mining or flour milling produce very fine and tiny particles
These particles have a very large surface area and are combustible in air
Even a small spark may cause them to ignite and since the surface area is so large, the rate of reaction can be incredibly fast, hence they are explosive
Methane gas mixed with air in coal mines can also form an explosive mixture
The shape of the graph shows a lot about the reaction going on.
Compared to a reaction with lumps of reactant, the graph line for the same reaction but with powdered reactant has a steeper gradient at the start and becomes horizontal sooner
This shows that with increased surface area of the solid, the rate of reaction will increase
Compared to a reaction at a low temperature, the graph line for the same reaction but at a higher temperature has a steeper gradient at the start and becomes horizontal sooner
This shows that with increased temperature, the rate of reaction will increase