Topic 16 Kinetics HL
16.1 Rate expressions ​
This video provides an introduction to rate expressions.
16.1 Orders of reaction 
Understandings:
The order of a reaction can be either integer or fractional in nature. The order of a reaction can describe, with respect to a reactant, the number of particles taking part in the rate-determining step.
Applications and skills:
Deduction of the rate expression for an equation from experimental data and solving problems involving the rate expression.
Note that the IB sometimes refers to orders of reaction as partial orders of reaction. In this video, I use the term orders of reaction. 
16.1 Reaction mechanisms 
This video covers how to deduce to the overall equation from the reaction mechanism and also how to deduce the rate expression from the elementary steps. 
16.1 Rate-determining step 
Understandings:
Reactions may occur by more than one step and the slowest step determines the rate of reaction (rate determining step/RDS).
16.1 Energy level profiles 
This video shows how to identify the transition states and intermediates in an energy level profile.
16.1 Molecularity 
Understandings:
The molecularity of an elementary step is the number of reactant particles taking part in that step.
16.1 Sketch, identify and analyse graphical representations for zero-, first- and second-order reactions.
Applications and skills:
Sketching, identifying, and analysing graphical representations for zero, first and second order reactions.
16.1 Catalysts 
Understandings:
Catalysts alter a reaction mechanism, introducing a step with lower activation energy.
Guidance:
Catalysts are involved in the rate-determining step.
16.2 The Arrhenius equation 
Note that in the video, I use the term 'fraction of collisions with energy equal to or greater than the activation energy'. This is the same as saying 'the fraction of particles with energy equal to or greater than the activation energy'. So as temperature increases the fraction of particles with energy equal to or greater than the activation energy also increases (the IB prefers to use this expression). 
Note that the IB definition of the Arrhenius constant (A) indicates the frequency of collisions and the probability that collisions have proper orientations. 
Understandings:
The Arrhenius equation uses the temperature dependence of the rate constant to determine the activation energy.
The frequency factor (or pre-exponential  factor) (A) takes into account the frequency of collisions with proper orientations.
16.2 Effect of temperature in the rate constant k 
Applications and skills:
Describing the relationships between temperature and rate constant; frequency factor and complexity of molecules colliding.
16.2 Calculating activation energy 
Understandings:
A graph of 1/T against ln k is a linear plot with gradient – Ea / R and intercept, lnA.
Applications and skills:
Analysing graphical representation of the Arrhenius equation in its linear form
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