Kinetics Flashcards
(20 cards)
Activation Energy
The minimum amount of energy which molecules need to collide to start a reaction.
5 Things dealing with Collision Theory
- Temperature
- Pressure
- Concentration
- Surface Area
- Catalyst
What is the area underneath the curve?
Total Number of molecules
Sometimes they reject particles, so always use molecules.
What is C and D
C: Represents the most probable energy
D: Represents the mean energy as the curve is not symmetrical
Why in the Maxwell-Distribution graph, does it start at zero?
This is because no particles have no energy
Thus, all particles have energy
How does the graph shift when temperature decreases?
Shifts to the left
How does the graph shift when the temperature increases?
It shifts to the right. The increase in kinetic energy broadens and flattens the curve due to a greater spread of values.
What happens to the activation energy when there is an increase/decrease in temperature?
The activation energy does not change.
An increase in temp means that more particles can react; more kinetic energy; increase of successful collisions; many more molecules have energy greater than the activation energy.
A decrease in temp means less particles can react; less kinetic energy; decrease of successful collisions
What is a catalyst?
A substance that speeds up the reaction
But is chemically unchanged at the end
How do catalysts work?
It lowers the activation energy
And provides an alternative pathway for the reaction to take place
What does the graph look like when a catalyst is introduced?
What does the graph look like when concentration or pressure increases?
What is the definition of rate of reaction?
Change in concentration of a substance in unit time
What is the unit of rate of reaction?
What does a concentration-time graph look like?
Draw the experimental set-up for rates of reaction
Explain the process that causes some molecules to have very low energies
Collisions cause some molecules to slow down or lose energy
What is the method of increasing the proportion of successful collisions?
By using a catalyst - lowers the activation energy by providing another pathway for the reaction to occur and this means more particles successfully collide frequently so they have greater energy than the activation energy
Explain what happens to the particles when increasing temp
The rate of reaction increases
Because more particles frequently and successfully collide due to an increase in kinetic energy
More particles have the minimum energy to collide successfully
There is a higher proportion of particles that have energy greater than the activation energy
Explain what happens to particles when increasing concentration
More reactant particles in a given area in the solution
Increases the rate of reaction because more particles have a chance of successfully colliding and reacting with each other frequently
