16.2 Activation energy
Essential Idea:
The activation energy of a reaction can be determined from the effect of temperature on reaction rate.
Understandings:
- The Arrhenius equation uses the temperature dependence of the rate constant to determine the activation energy.
- A graph of 1/T against ln k is a linear plot with gradient – Ea / R and intercept, lnA.
- The frequency factor (or pre-exponential factor) (A) takes into account the frequency of collisions with proper orientations.
Applications and Skills:
- Analysing graphical representation of the Arrhenius equation in its linear form \(ln\;k = \frac{-E_a}{RT}+ln \;A\)
- Using the Arrhenius equation \(k=Ae^{\frac{-E_a}{RT}}\)
- Describing the relationships between temperature and rate constant; frequency factor and complexity of molecules colliding.
- Determining and evaluating values of activation energy and frequency factors from data.