3.2 Controlling the rate Flashcards
collision theory
Reaction rates must be controlled in industrial processes. If the rate is too low then the process will not be economically viable, if it is too high there will be a risk of explosion.
what effects on reaction rates can be explained with the collision theory?
concentration
pressure
surface area (particle size)
temperature
collision geometry
enthalpy change
The enthalpy change is the energy difference between the products and the reactants. The enthalpy change has a negative value for exothermic reactions or a positive value for endothermic reactions.
activation energy
The activation energy is the minimum energy required by colliding particles to form an activated complex and can be calculated from potential energy diagrams
activated complex
The activated complex is an unstable arrangement of atoms formed at the maximum of the potential energy barrier, during a reaction.
effect of catalyst on reaction pathway
A catalyst provides an alternative reaction pathway with a lower activation energy.
Temperature
Temperature is a measure of the average kinetic energy of the particles in a substance.
Activation energy
The minimum kinetic energy required by colliding particles before a reaction may occur
How can you explain the effects of temperature and adding a catalyst?
In terms of a change in the number of particles with energy greater than the activation energy