C6 Flashcards
What is the rate of reaction?
How quickly the reactants turn into products
What are the two equations for rate of reaction?
HOW QUICKLY THE REACTANT IS USED UP- Mean rate of reaction= quantity of reactant used/ time taken
HOW QUICKLY THE PRODUCT IS PRODUCED- Mean rate of reaction= quantity of product formed/time taken
What is the rate of reaction if there is a change in mass?
Rate= change in mass/ time taken
The unit is g/s
What is the rate of reaction if there was a volume of gas produced?
Rate= volume of gas produced/ time taken
If the gradient on a graph is high/ low, what does it tell you about the rate of reaction?
Steep gradient- high rate of reaction= reaction happens quickly
Shallow gradient- low rate of reaction= reaction happens slowly
How can you increase the rate of reaction?
Increasing the frequency of collisions
Increasing the energy of the particles when they collide
What is the activation energy?
The energy required to start a reaction when particles collide. When the particles do not have the activation energy, they will just bounce apart
How does increasing the temperature affect the rate of reaction?
Heating the container in which the reaction is taking place, they particles move faster, leading to more frequent collisions. This means the particles will have more energy, so more collisions will result in a reaction
How does increasing the concentration of solutions affect the rate of reaction?
Using a solution with more solute in the same volume of solvent means there are more reactant particles in the reaction mixture, so collisions become more frequent
How does increasing the pressure of gases affect the rate of reaction?
Increasing the number of gas particles you have in the container or making the container smaller will create less space between particles so there are more frequent collisions
How does increasing the surface area of solids affect the rate of reaction?
Cutting the solid into smaller pieces, or grinding it into power will increase the surface area. The greater the surface area, the more reactant particles are exposed, leading to more frequent collisions
What are catalysts?
Specific substances that can be added to some reactions to increase the rate of reaction . These aren’t used up in the reaction
What do catalysts do?
A catalyst provides a different reaction pathway that has a lower activation energy. Thus, more particles will collide with enough energy to react, so more collisions will result in a reaction
What to note about graphs showing progress of reactions?
The steeper the line, the faster the reaction
The steepness of the line is about the rate of reaction
The height it reaches is about the reacting quantities
Fastest at the beginning when there is a lot of reactants to use, slows down because there are fewer reactants to use up and it comes to a stop when the reactants have been used up
How to calculate the rate of reaction from a graph?
The average rate of reaction is calculated by the product formed OR reactants lost/ time
When calculating the rate of reaction at a specific moment, a tangent is used:
Draw a straight line to the curve at the specific time
Make a triangle, with the tangent as the hypotenuse
Calculate the gradient
What is equilibrium?
When the rate of the forward reaction is equal to the rate of the backward reaction IN A CLOSED SYSTEM (a system where there is no external influence)
What to note about the arrows in the rate of the forward and backward reaction?
They must be slightly proportional
E.g. if the forward reaction was much larger than the backwards, the forward arrow must be much larger than the backward one
If the backward reaction is twice as large than the forward, the backward arrow must be twice as big as the forward one
What does the system do if I increase the temperature of the reaction?
It will decrease the temperature by moving towards the endothermic reaction
What does the system do if I decrease the temperature of the reaction?
It will increase the temperature by moving towards the exothermic reaction
What does the system do if I increase the concentration of the reactants?
It decreases the amount of products made by favouring the FORWARD reaction
What does the system do if I decrease the concentration of the reactants?
It will increase the amount of products made by favouring the BACKWARD reaction
What does the system do if I increase the pressure?
It reduces the change in pressure by shifting to the side of the equation that has the FEWEST MOLECULES OF GAS
What does the system do if I decrease the pressure?
It will reduce the change in pressure by shifting to the side of the equation that has the MOST MOLECULES OF GAS
