Rates of reaction Flashcards
What 4 things affect the rate of reaction?
Catalyst
Concentration/pressure
Surface area
Temperature
What is it called when a collision of molecules is strong enough to break the old bonds and make new ones?
Successful or effective collision
What is it called when a collision of molecules isn’t strong enough to break the existing bonds?
Unsuccessful it ineffective collision
What is activation energy?
The minimum energy that a pair of colliding molecules need in order to react.
Apart from the activation energy what is something 2 molecules need in order to react?
They need the correct orientation
Why does increasing surface area of a solid increase the rate?
The rate depends on the frequency of successful collisions.
More molecules are exposed for collisions so they collide more frequently.
Therefore, there are more successful collisions per second.
Why does increasing the concentration of a solution increase the rate?
The rate depends on the frequency of successful collisions.
More molecules in a given volume so there will be more collisions per second.
Therefore, there are more successful collisions per second.
Why does increasing the pressure of a gas increase the rate?
The rate depends on the frequency of successful collisions.
Molecules move closer, more molecules in a given volume so more collisions per second.
Therefore, there are more successful collisions per second.
Why does increasing the temperature increase the rate?
The rate depends on the frequency of successful collisions.
Molecules have more kinetic energy, collide more frequently and more have at least the activation energy and can react when they collide.
Therefore, there are more successful collisions per second.
Why does using a catalyst increase the rate?
The rate depends on the frequency of successful collisions.
Provides an alternative pathway of lower activation energy so more molecules have at least the activation energy.
Therefore, there are more successful collisions per second.
What is the collision theory?
In order for a reaction to occur, two particles must collide with the correct orientation and with at least the activation energy.
What are the benefits of using a catalyst?
Lower temp needed Costs are lower Less emissions Fewer fossil fuels used More sustainable
What is a homogeneous catalyst?
Catalyst in the same state as reactants
What is a heterogeneous catalyst?
Catalyst in a different state to the reactants
What type of system is needed for a dynamic equilibrium to be set up?
A closed system
