Rate determining step
Rate equations
Rates and orders
Define the term ‘reaction rate’
Pick a suitable way of recording the reaction rate for a given set of
Calculate a reaction rate from the gradient of a concentration-time
Use a concentration-time graph to plot a rate-concentration graph
Sketch rate-concentration graphs for zero, first and second order
Determine the order of a reactant limited to zero, first and second
orders, from a data set or the graphs mentioned above
Explain the effect on rate of reaction of doubling or tripling
concentration of a zero, first or second order reactant
Write a rate equation CARE: do not include zero order reactants
Know the units of rate are mol dm-3 s-1
Determine the overall order for a reaction
Understand the need for the rate constant, k. Explain when it will
change and calculate a value from a rate equation
Determine units for the rate constant, k
Know how the rate constant changes with temperature, and the effect
this has on the rate of reaction
Understand the meaning of the term ‘rate determining step’
Know that reactants in the rate equation will be involved in the rate
determining step
Know that the order of reaction with respect to a reactant shows the
number of molecules of it involved in the rate determining step
Be able to write a rate equation from a rate determining step using the
above rule
Predict whether a mechanism is likely or not by comparing it with
the rate-determining step
Exam ques
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A2 Chemistry – Unit 4