rate of reaction

What factors affect the rate of reaction

temperature

concentration of pressure

surface area

the presence of a catalyst

How does temperature increase the rate of chemical reaction?

When the temperature is increased then this causes the particles to move faster. This causes more frequent collisions

how does concentration increase the rate of chemical reaction

A greater concentration means that there is ore particles knocking about in the same volume of water. This means more frequent collisions

how does pressure increase the rate of reaction

A larger pressure of a gas means that the more particles occupy a smaller space meaning more frequent collisions

How does surface area increase the rate of reactions

If one of the reactants is a solid then breaking it up into smaller pieces will increase its surface area to volume ratio. This means that for the same volume of solid the particles will have a greater area to work on meaning their will be more frequent collisions

how does a catalyst increase the rate of reactions?

they provide a different reaction pathway which has a lower activation energy. This means more particles will collise with enough enegry to react so there will be more collisions

what does the collision theory state

For a reaction to occur the particles need to collide. When the particles collide they need to have energy to react or they will just bounce apart.

what does the rate of a chemical reaction depend on?

• the collsion frequency of reacting particles. The more collisions the faster the faster the reaction

• The energy transferred during the reaction. Particles have to collide with enough energy in order to be successful.

what is a reversible reaction?

Reactions where the products react to produce the orginal reactants

In a reversible reaction what happens if the equilibrium is at the right or left ?

The concentration of products is greater than the reactants. If it lies to the left then the concentration of reactants is greater than products.

What does it mean if a system is at equilibriu,?

The forward reaction is going at exactly the same rate as the backward one

What happens during equilibrium?

both reactions are happening but their is no overrall effect(dynamic equilibrium). This means that the concentration of reactants and products have reached a balance and wont change.

When will equilibrium be reached?

Only if the reversible reactio takes place in a closed system therefore none of the reactants and products can escape

What is Le chateliers principle ?

The idea that if you change the conditions of a reversible reaction at equilibrium, the system would try and counteract the change. It can be used to predict the effect of any changes you make to the reaction system

what is the effect of changing the temperature in a reaction system?

If you decrease the temperature, the system would move in the direction of the exothermic to produce more heat. This imeans that you will get more products for the exothermic and fewer for the endothermic.

If you raise the temperature then the equilibrium will move in the direction of the endothermic to try and decrease it. You will now get more products for endothermic and fewer for the exothermic.

whats the effect of changing the pressure in a reaction system

if you increase the pressure then the equilibrium will try and reduce it meaning ti will move in the direction where there are fewer molecules of gas

if you decrease the pressure then the equilibrium will try and increase it meaning it will move in the direction where there are more molecules of gas