(L16) - M2 L6 - Chemical Kinetics Flashcards
How does rate of reaction depend on temperature?
rate = k[A]a[B]b
k depends on temperature.
so rate proportional to k.
What 3 factors affect rate at which molecules react?
- collision rate
- collision effectiveness
- collision orientation
How does collision rate affect rate of reaction?
more collisions = increased reaction rate
more temp = more KE = more collisions = increased reaction rate
What factors effect rate of reaction?
- concentration of reactants
- greater speed (more KE) more collisions
How does collision effectiveness affect rate of reaction?
Even if Gibb’s law is negative and reaction is spontaneous, energy is till required to overcome activation energy and for reaction to begin.
- Not all collisions lead to a reaction
What factors effect effectiveness of rate of reaction?
temperature, temp increases raises energy which means more chance of overcoming activation energy.
Approximate rule of thumb.
With every 10C increase, rate of reaction doubles.
What is collision orientation?
Molecules must be orientated correctly during collision for reaction to occur.
What is molecularity?
Number of species involved in a single collision leading to a reaction
what is classification of molecularity 1, 2 and 3?
1 - unimolecular
2 - bimolecular
3 - termolecular (unlikely)
What is transition state?
Collisions form loosely bound complex made up of partially formed and partially broken bonds.
denoted by superscript ‡
Exists for very short time
Can not be isolated
Either forms
- products (effective collision)
or
- returns to reactants (ineffective collision)
What is frequency factor?
Ae, indicates frequency of collisions which are favourably orientated to cause reactions.
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