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IB DP Chemistry: HL复习笔记16.2.2 Graphing the Arrhenius Equation

Category: IB课程, 教材笔记, 福利干货 Date: 2022年7月29日上午11:53

Graphing the Arrhenius Equation

Finding the Activation Energy

Very often, the Arrhenius equation is used to calculate the activation energy of a reaction
A question will either give sufficient information for the Arrhenius equation to be used or a graph can be plotted and the calculation done from the plot

Using the equation:

Remember, it is usually easier to use the version of the Arrhenius equation after natural logs of each side have been taken

Using an Arrhenius plot:

A graph of ln k against 1/T can be plotted, and then used to calculate E_a
- This gives a line which follows the form y = mx + c

5.2.5-Arrhenius-sketch-of-ln-k-against-1_T_2

The graph of ln k against 1/T is a straight line with gradient -E_a/R

From the graph, the equation in the form of y = mx + c is as follows:

5.2.5-Y-mx-c-from-Arrhenius-graph_2

Worked Example

Complete the following table
Plot a graph of ln k against 1/T
Use this to calculate the activation energy, E_a, and the Arrhenius constant, A, of the reaction.

5.2.5-Calculate-the-activation-energy-from-the-Arrhenius-plot-WE

Answers

Answer 1: 5.2.5-Using-Arrhenius-plot-to-calculate-Ea-calculation-answer-complete-table-WE_1

Answer 2: 5.2.5-using-Arrhenius-plot-to-calculate-Ea-plotted-graph-WE_2

Answer 3: 5.2.5-WE-Arrhenius-plot-calculate-Ea-1_1

5.2.5-WE-Arrhenius-plot-calculate-A-part-2_2

Exam Tip

You are not required to learn these equations.However, you do need to be able to rearrange them, and knowing them is helpful in understanding the effects of temperature on the rate constant.

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