Unit 3 Flashcards
Describe the impacts to industry when a reaction is too slow and when it is too fast.
When too slow, the process is not economically viable.
When too fast, there is chance for explosion.
State the 3 factors of collision theory.
Particles must collide.
They must do so with at least the activation energy.
They must collide with correct orientation/geometry.
How do you calculate average rate?
When would you use it?
Average rate = △Q/△T
When finding the rate of a reaction between two fixed points of the reaction.
How do you calculate relative rate?
When would you use it?
Relative Rate = 1/t
When monitoring reactions with a unit that cannot be measured. e.g. color change.
Define the term activation energy.
Minimum amount of energy required to form an activated complex.
Define the term activated complex.
A high energy unstable intermediate of atoms that exists at the peak of the potential energy barrier.
Why does increasing pressure increase reaction rate?
Pushes particles closer together, causing a localised increase in concentration.
This allows for particles to collide more often increasing reaction rate.
How does a catalyst increase reaction rate?
Creates alternate pathway with lower activation energy, therefore particles are more likely to have sufficient energy.
This allows for more successful collisions therefore a higher rate.
How does decreasing particles size increase reaction rate?
Allows for more surface area for collisions to take place on.
This allows for particles to collide more often increasing rate.
How does increasing concentration increase reaction rate?
Allows for more reactant particles.
This allows for particles to collide more often increasing rate.
How does increasing temperature increase reaction rate?
Higher temperature means each particle has more energy, therefore move faster and are more likely to have sufficient energy to overcome the activated complex.
This allows for particles to collide more often, doing so successfully; increasing rate.
How does temperature affect the energy distribution diagram?
It lowers it and shifts it to the right, this in turn increases amount of particles with sufficient energy.
How does a catalyst affect the energy distribution diagram?
It moves the activation energy line to the left, this in turn increases amount of particles with sufficient energy.
Describe the energy pathways on a potential energy diagram for an exothermic reaction.
Will the enthlapy change be positive or negative?
The reactants are drawn above the products.
The enthlapy change will be negative since the reaction is giving out heat.
Describe the energy pathways on a potential energy diagram for an endothermic reaction.
Will the enthlapy change be positive or negative?
The reactants are drawn below the products.
The enthlapy change will be positive since the reaction is taking in heat.
