Effect of temperature on reaction rates and the concept of activation energy — common mistakes

When drawing or interpreting Boltzmann distribution curves, always label the axes correctly ('Number of particles' vs 'Kinetic energy'). When comparing two temperatures, ensure the curve for the higher temperature (T2) has a lower peak, is shifted to the right, and crosses the lower temperature (T1) curve only once. Crucially, show that both curves start at the origin and neither touches the x-axis at high energy.

When asked to explain the effect of temperature on rate, you must mention both increased collision frequency and the increased proportion of particles with $E \ge E_a$. However, always state that the second factor is far more significant. A common mistake is to only mention one of the two points.

No, this is a common misconception. The activation energy ($E_a$) is a fixed property for a specific reaction pathway. Increasing the temperature increases the kinetic energy of the reactant particles, meaning a greater proportion of them have enough energy to overcome the fixed $E_a$ barrier. The barrier itself does not change.

No. The peak represents the 'most probable' energy, not the total number of reactive particles. At a higher temperature, the energy distribution spreads out. While fewer particles have the 'most probable' energy, the overall average energy is higher, and crucially, a much larger proportion of particles is found at the high-energy end of the curve, beyond the activation energy. This larger number of high-energy particles is what increases the reaction rate.

Not necessarily. For a collision to be 'successful' or 'effective', two conditions must be met: the particles must possess energy equal to or greater than the activation energy, AND they must collide with the correct geometric orientation. Simply having enough energy is not sufficient if the particles are not correctly aligned to allow bonds to break and form.