Rates Of Reaction-PAPER2 Flashcards
What is the rate of a reaction?
How quickly the reactants change into the products
What is meant by activation energy?
The minimum amount of energy that particles need to react
Why do particles need lots of energy?
To break bonds in the reactants and begin the reaction.
What factors affect the speed of the reaction?
Temperature
Concentration or pressure
Surface Area
A catalyst
How does temperature increase the rate?
As when the temp is increased the particles move faster so collide more frequently.
How does the concentration or pressure affect the rate of reaction?
The more concentrated a solution is, the more particles in that same volume.
Similarly with gas more particles and in a smaller space
This makes collisions more frequent
How does increasing the surface area increase the rate?
As if a solid in broken up, for the same volume of a solid the particles will have more area to work on so there will be more collisions.
How does a catalyst speed up the rate of reaction?
They decrease the amount of activation energy need for the reaction to occur. They do this by providing an alternative pathway, with a lower activation energy.
How can you measure the rate of reaction?
Measure the volume of gas given off (use gas syringe) or calculate the change in mass.
How to calculate the rate of reaction at any point on a graph?
Gradient (change in y/change in x)
What equipment is need to calculate the reaction rate of Mg and HCl reacting to H2 gas?
Comical flask
Cotton wool
Mass balance (scales)
Stopwatch
What is Le Chateliers Principle?
The idea that if you change the conditions of a reversible reaction at equilibrium the system will try and counteract that change.
What happens if you change the pressure?
If you increase it the equilibrium moves in the direction where there are fewer molecules of gas
And vice versa
If you change the concentration at equilibrium what happens?
The system will no longer be at equilibrium, so will try to regain equilibrium by making more products or reducing the amount of reactants
What are reaction rates explained perfectly by?
collision theory
