Kinetics Flashcards
-define collision theory
Reactions can only occur when collisions take place between particles having sufficient energy
This energy is called the activation energy.
-define activation energy
minimum energy which particles need to collide to start a reaction.
-Why do most collisions not lead to a reaction?
If the particles don’t have enough energy or don’t collide in the correct orientation.
-what does the Maxwell Boltzmann distribution show
spread of energies that
molecules of a gas or liquid have at a particular temperature
-draw out the Maxwell Boltzmann distribution
-Draw and interpret distribution curves for different temperatures
state the meaning rate of reaction
change in concentration of a substance in a given time
-draw the endothermic reaction graph
-draw the exothermic reaction graph
-What is the qualitative effect of temperature changes on the rate of reaction
-average speed of particles increases
-particles have the Ea needed to react
-rate of reaction increases
-How does increase of temperature effect the reaction?
-particles have more KE so they move faster
-more successful collisions per second
-greater proportion of collisions have energy greater than the Ea
-more successful collisions, higher rate of reaction
- Maxwell-Boltzmann distribution to explain why a small temperature increase can lead to a large increase in rate
-Increasing temp increases proportion of particles that have the minimum Ea to react.
-This increases the shaded area on the graph; rate of reaction increases.
what is Emp
most probably energy
Effect of increasing concentration
more particles perunit volume and
so the particles collide with a greater frequency
and there will be a higher frequency of effective collisions.
Will the area under the curve differ when the concentration is increased?
Yes because there are more particles, meaning the peak will be higher
Why should the energy distribution go through the origin on the graph?
There are no molecules with no energy
effect of increasing the surface area
Increasing surface area will cause successful collisions to occur more frequently between the reactant particles
and this increases the rate of the reaction.
definition of catalysts
a substance that speeds up chemical reaction without being used up
Explanation of how they do this
They do this by providing an alternative route with a lower activation to increase the rate of reaction
what happens when the activation energy is lower?
more particles will have energy greater than the EA, so there will be a higher frequency of effective collisions. The reaction will be
faster.
What happens to the proportion of molecules exceeding the activation energy when a catalyst is present?
The proportion increases as the activation energy is lower.
What happens to the rate of reaction when a catalyst is introduced?
it increases
