Rates of Reaction Flashcards
(20 cards)
What is reaction rate?
The change in concentration of a reactant or product over time
What is the equation for rate of reaction?
Rate of reaction = amount of reactant used or product formed / time
What is the collision theory?
In order for a reaction to occur, particles must collide in the right direction and with at least a certain minimum amount of kinetic energy
What is activation energy?
The minimum amount of kinetic energy that particles need to react.
What is enthalpy?
The total heat content of a system
By increasing temperature, what does this do to the rate of reaction?
Increasing the temperature means particles will have more kinetic energy, and so they’ll move faster and will therefore collide more frequently.
By increasing concentration, what does this do to the rate of reaction?
As concentration increases, particles will be closer together, and so they will collide more frequently, and the chances of a reaction will therefore be higher.
By increasing pressure, what does this do to the rate of reaction?
As the pressure increases, gas particles will therefore be closer together, therefore causing more collisions, and the chance of a reaction will therefore be higher.
What are catalysts?
They are substances that increase the rate of a reaction by providing an alternative reaction pathway with a lower activation energy.
Catalysts are what at the end of every reaction?
Chemically unchanged
What are enzymes?
Enzymes are biological catalysts that function by modifying substrate molecules to promote reactions
What is the rate equation?
Rate = k[A]^m[B]^n
How do you work out the overall order of a reaction?
m + n
Where can you find orders of reaction from?
Only from experiments.
What would happen if you changed [A] and the rate stayed the same?
Then the order of reaction with respect to A is 0
What would happen if the rate were proportional to [A]?
Then the order of reaction with respect to A is 1 (if A doubles, the rate will double)
What will happen if the rate is proportional to [A]^2?
The order of reaction with respect to A is 2. (If A doubles, then the rate will be four times faster)
In concentration-time graphs, what direction are they going in?
0 - straight down diagonally
1 - down but curved
2 - down but very steeply curved
In concentration-rate graphs, what direction are they going in?
0 - straight line across ———
1 - straight line diagonally upwards
2 - curved upwards very steeply
What is the rate-determining step?
The rate with greatest activation energy (the slowest step)
