Controlling The Rate Flashcards
Why are reaction rates controlled in industrial processes?
If reaction rates are too low the process will not be economical.
If the reaction rates are too high there will be a risk of an explosion.
What is the formula to calculate the relative rate?
relative rate = 1/t
How does concentration affect reaction rates?
The higher the concentration the more particles there are so this increases the chances of successful collisions.
How does Particle size affect reaction rate?
Decreasing the particle size the bigger the surface area will be so this allows more ‘space’ for collisions to occur.
How does Temperature affect reaction rates?
The higher the temperature the more energy the particles have, which causes them to move faster, increasing chances of a collision.
How does pressure affect the reaction rate?
For gaseous reactants, if pressure is increased there are more reactant particles for a given volume so there will be more collisions.
How does collision geometry affect reaction rates?
The particles must collide with the correct geometry for the reaction to be successful
What does the potential energy diagram look like for an exothermic reaction?
The energy of the products is less than the energy of the reactants, which gives it a -ve enthalpy.
What does the potential energy diagram look like for an endothermic reaction?
The energy of the products is more than the energy of the reactants, gives it a +ve enthalpy.
Give the definition of enthalpy change:
The enthalpy change is the difference in energy between the products and the reactants.
What is the activation energy?
The activation energy is the minimum energy required by the particles to form an activated complex
What happens if the colliding particles don’t have any activation energy?
The collision does not take place.
How do you find the activation energy on a potential energy diagram?
The Ea is the difference between the highest energy and the energy of the reactants.
What is the activated complex?
The Activated complex is the unstable arrangement of atoms at the top of the potential energy barrier (top of the graph).
How do catalysts affect activation energy?
Catalysts provide an alternative pathway for reactants. The alternative pathway will have a lower activation energy which means that more particles will have sufficient energy to collide.
