Topic 6.2.4 · Rates of Reaction
Temperature: The Double Whammy 🌡️🔥
Why does heating a reaction not just make it a little faster — it makes it dramatically faster.
🎯 The Story: Imagine you're a talent scout at a high-jump championship. The bar represents the Activation Energy (Ea) — the minimum energy needed to react. Cold athletes (cold particles) are sluggish. Only a tiny fraction can clear the bar. Give them energy drinks (🔥 heat) and suddenly almost everyone clears it. That's the Double Whammy.
10°C (Fridge)55°C (Warm)100°C (Boiling)
☑️ The Double Whammy Checklist
Whammy 1 — Collision Frequency
⏸ Increase temperature to check...
Whammy 2 — Collision Success Rate
⏸ Increase temperature to check...
⚠️ Examiner Trap: Students write "particles collide more" and lose marks. The Cambridge mark scheme demands both effects — especially that a greater proportion of particles have energy ≥ Ea.
⚗️ Live Particle Simulation
Active collisions: 0 /frameSpeed: 1.2×
🔬 Macro observation: Faster reaction. Micro explanation: More frequent collisions AND a greater proportion exceed Ea.
📋 Cambridge Golden Keywords (6.2.4)
Kinetic Energy
Energy of movement — increases with temperature
Activation Energy (Ea)
Minimum energy needed for a successful collision
Collision Frequency
Number of collisions per unit time
Successful Collision
One where both particles have energy ≥ Ea
Maxwell-Boltzmann
Distribution curve showing particle energies
Rate of Reaction
Change in amount of reactant/product per unit time
⚠️ Examiner Traps — Don't Lose Marks!
✗ "Higher temperature makes particles move faster and collide more." — Incomplete! Only gets 1/2 marks.
✓ "Higher temperature increases kinetic energy so particles collide more frequently AND a greater proportion of particles have energy ≥ Ea, so more collisions are successful."
✗ "Temperature gives particles more energy." — Vague. Say kinetic energy.
✗ "More collisions happen." — Must say more frequent collisions.
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