Controlling The Rate Flashcards
What must be controlled in industrial processes?
Reaction rates
What happens if the rate is too low in an industrial process?
The process will not be economically viable
Eg. May not generate a profit
What happens if the rate is too high in an industrial process?
There will be a risk of explosion
How do you measure relative rate?(s-1)
1/t
Where t is time taken for reaction to reach a certain point
What does collision theory state?
That for a successful chemical reaction to occur reactant particles must collide with each other, with the correct collision geometry/orientation and the right amount of energy a successful collision will occur
What is the relationship between concentration/pressure and rate of reaction?
Why?
Increasing the concentration/pressure increases the rate of reaction
As there are more particles moving about so the chance of collision is increased, increasing the chance of successful collisions
What is the relationship between particle size and rate of reaction?
Why?
Decreasing particle size/increasing surface area increases the rate of reaction
As there are more surfaces exposed so more particles are able to react so increased number of collisions
What is temperature?
A measure of the average kinetic energy of all particles in a substance
What is the relationship between temperature and rate of reaction?
Increasing the temperature increases the rate of reaction
The average kinetic energy of the particles is increased so more particles have the minimum kinetic energy needed to react(activation energy) so more successful collisions
What is activation energy?
The minimum kinetic energy required by colliding oarticles for a reaction to occur
What is collision geometry?
The position of the reactants when they collide
What can a potential energy diagram be used to show?
The energy pathway for a reaction
What is the enthalpy change(/_\H)
The energy difference between the products and the reactants
What is enthalpy change measured from in a forward reaction?
From reactants to products
What is enthalpy change measured from in a reverse reaction?
Form products to reactants
What is the enthalpy change in exothermic reactions?
The enthalpy change is a negative value showing energy is lost to the surroundings(products have less energy than reactants)
What is the enthalpy change in an endothermic reaction?
The enthalpy change is a positive value showing energy is gained form the surroundings(products have more energy than reactants)
What is the activated complex?
An unstable arrangement of atoms, formed at the maximum(top) of the potential energy barrier(diagram) during a reaction
What is a catalyst?
What does a catalyst do?
Speeds up chemical reactions without being used up
Provides an alternative reaction pathway with a lower activation energy
What effect does a catylast have on activating energy and enthalpy change?
Lowers activation energy
Enthalpy change remains unchanged
What does increasing and decreasing temperature do in energy distribution diagrams?
Increasing-moves curve to right(more particles greater energy than Ea)
Decreasing-moves curve to left
What does a catalyst do to an energy distribution diagram?
Lowers the activation energy(moves Ea line to the left)
