The Arrhenius Equation: Mastering Reaction Rates in IB Chemistry (Reactivity 2.2)

The Arrhenius Equation is a fundamental concept in the IB Chemistry curriculum, particularly in the topic of chemical kinetics. It explains how temperature and activation energy influence the rate of chemical reactions, offering students a powerful tool to understand why reactions occur at different speeds under varying conditions.

Understanding the Components

Activation Energy (Eₐ): A critical factor in determining how fast a reaction proceeds. Reactions with lower activation energies occur more quickly, while those with high activation energies are slower. The Arrhenius Equation helps students appreciate the link between activation energy and reaction kinetics.
Temperature (T): The equation highlights how an increase in temperature can exponentially accelerate the rate of a reaction by providing more molecules with enough energy to surpass the activation energy.
Pre-exponential Factor (A): Although often overlooked, the pre-exponential factor plays an important role in determining the frequency of successful collisions. In the IB Chemistry syllabus, students learn that this term accounts for both the number of collisions and the correct molecular orientation needed for reactions. A more complex (complicated large structure) molecule has a lower A value.