The Arrhenius Equation illustrates the temperature dependence of the rate constant k.
Temperature is one of the four factors that directly affects the rate of a reaction. It affects the rate of a reaction by impacting the rate constant k.
Concept #1: The Arrhenius Equation
The Arrhenius Equation shows the dependence of the rate constant on the pre-exponential factor, absolute temperature and activitation energy of the reaction.
In terms of what makes for a fast rate we can relate all these variables together.
Concept #2: Besides the general Arrhenius equation there are also the two-point form and the linear/graphical form.
When dealing with TWO rate constants or TWO temperatures then we use the Two-Point Form of the Arrhenius Equation.
In order to relate the plot of a graph to the Arrhenius equation then we manipulate it into the plot-wise approach of the equation.
Example #1: The reaction 2 HCl (g) → H2 (g) + Cl2 (g) has Ea of 1.77 x 104 kJ/mol and a rate constant of 1.32 x 10-1 at 700 K. What is the rate constant at 685 K?
Practice: If a first order reaction has a frequency factor of 3.98 x 1013 s-1 and Ea of 160 kJ, then calculate the rate constant at 25oC.
Practice: Generally, the slower the rate of the reaction then the ___________ the energy of activation (Ea) and the higher the temperature, the ____________ the value of rate constant, k.