Kinetics
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What is kinetic or rate
How fast a reaction occurs
What is collision theory
For a reaction to occur particles must collide with an energy more than or equal to that of the activation energy
Define activation energy
Minimum energy for reaction to occur/ for succesfull collisions to occur
Describe reaction profile diagram for exorthemric reaction
Recants have more energy then prod Change in H arrow goes down
factors affecting rate of reaction
Temp Conc Pressure Catalyst Surface area
Describe effect of temp on rate of reaction
Increased temp means increased kinetic energy of particles So particles move faster and collide more often Thus increased likelihood of successful collisions
What is meant by succesful collision
Collisions wiht enough energy to overcome activation energy giving a faster rate of
Describe conc effect on rate
Increased conc Particles closer together more particles per unit volume More collisions More succesfull collisions Increase rate
how will curve on graph change with an increase in pressure
If concentration increases, the shape of the energy distribution curves do not change (i.e. the peak is at the same energy) so the Emp and mean energy do not change. They curves will be higher, and the area under the curves will be greater because there are more particles.
Describe pressure effect on rate
For gases Same effect as conc more particles per unit volume So particles closer More collisions More sucessful collisions
what is a catalyst
Catalysts increase reaction rates without getting used up. Explanation: They do this by providing an alternative route or mechanism with a lower activation energy.
Describe catalyst effect on rate
Increases rate of reaction Catalyst provides alternative energy pathway for the reaction with a lower activation energy
describe effect of increased surface area on rate of reaction
Increasing surface area will cause successful collisions to occur more frequently between the reactant particles and this increases the rate of the reaction.
if you double concentration what happens to rate
double in rate double number of particles per unit volume double freq of sucessful collisons
Define rate of reaction
Change in conc of a substance over a unit time
What does it show when a graph levels off
No more gas is produced Gradient = rate - Rate is 0
what does the peak of the maxwell boltzman curve represent
most propable energy
what does area under graph on maxwell boltzman show
total number of particles present
what does the line on the right of the peak show
mean average energy
how would total area under graph change on mb graph at a higher temp
The total area under the curve should remain constant because the total number of particles is constant more succ coll bc more partivles met activation energt
Where does curve start and end on maxwells - Boltzman distribution
Starts at origin Ends just above x axis (representing energy)
Y axis on maxwell boltsnan represents
Number of particles
At a higher temp describe mb curve
Moves to the right - more particles at higher energy level Most probable energy has increased Lower and wider peak - area under curve must stay the same
At a lower temp mb curve…
Higher peak - a large number of particles have low energy Moves to the left