Molecules react only when they collide with enough energy to get over the barrier (the activation energy, Ea) and in the right orientation. Raising the temperature makes collisions only slightly more frequent, but it greatly increases the fraction that have enough energy. That is why reaction rates are so sensitive to temperature. Work through the three stages in order.
Was this lesson useful?
All feedback is anonymous. No names or logins are collected.
Your results
Temperature
A + B collisions
Enough energy
AB formed
Collisions that react
Remember
Arrhenius equation: k = A e−Ea/RT. The factor e−Ea/RT is the fraction of collisions with enough energy; A accounts for how often molecules collide and how often they are correctly oriented.
Use T in kelvin and Ea in J mol−1 when R = 8.314 J K−1 mol−1.
Comparing two temperatures: k2 ÷ k1 = e(Ea/R)(1/T1 − 1/T2). The higher the activation energy, the more sensitive the rate is to temperature.
The activation energy itself does not change with temperature. Only a catalyst (a different route) lowers it.
In the box in stage 1 the barrier is made much lower than in a real reaction, so that some collisions succeed while you watch. Stage 2 uses real values.
The counts in the box are random, like a real experiment: repeat a run at the same temperature and the numbers will differ a little. The trend with temperature is what matters.