Rates & Equilibrium Flashcards
Rate of reaction definition
Change in concentration / time
Describe and explain how concentration effects the rate of reaction
Increasing the concentration means there are more molecules per unit volume
The molecules will be closer together and so there is a greater chance of them colliding
There will be more collisions per second, and therefore more collisions with energy greater than the activation energy per second, so the rate of reaction will increase
Describe and explain the effect of pressure on the rate of reaction
Increasing the pressure means there are the same number of molecules in a smaller volumes
In a gaseous reaction, this is the same as increasing the concentration
So there will be more collisions per second and therefore more collisions with energy greater than the activation energy
Therefore the rate of reaction will increase
Activation energy definition
The minimum energy required to start a reaction by the breaking of bonds
Catalyst definition
A catalyst increases the rate of a chemic reaction by offering an alternate route for the reaction with a lower activation energy, without being used up in the process
What catalyst is used in the Haber process?
Iron
What catalyst is used the contact process?
V2O5
A dynamic equilibrium exists when…
The rate of forward reaction is equal to the rate of the reverse reaction
State le Chatelier’s principle
When a system in dynamic equilibrium is subjected to a change, the position of equilibrium will shift to minimise the change
Describe the effect of temperature on the position of equilibrium for an exothermic reaction
If the temperature is increased, the position of equilibrium will shift in the direction that decreases the temperature. The system opposes the change by taking in heat and the position of equilibrium shifts to the left, and moves in the exothermic direction
Explain how catalysts benefit the environment
Catalysts lower the activation energy. This means less energy is required for the molecules to react. This energy often comes from burning fossil fuels, which produces CO2, which contributes to climate change. The catalyst can also offer a different route for the reaction to happen, this route may have a higher atom economy, so less harmful waste is produced
