IGCSE Chemistry - Investigating Factors Affecting Reaction Rate
Higher temperature increases particle kinetic energy and collision frequency
Higher concentration increases number of acid particles available
Smaller particles expose more surface area for reactions
🔴 Red = Marble (limiting reagent) | 🔵 Blue = Acid (excess) | 💨 White = CO₂ gas
🟢 Green flash = successful reaction | 🟠 Orange flash = insufficient activation energy
Real-time plot of reaction progress
Reactions occur when reactant particles collide with sufficient energy (greater than activation energy). Not every collision leads to a reaction — watch for the colour flashes: green = successful reaction, orange = unsuccessful (not enough energy).
The minimum energy particles need to react on collision. At low temperatures, most collisions are unsuccessful because particles move slowly. At higher temperatures, a greater proportion of particles have energy exceeding the activation energy, so more collisions are successful.
Increasing temperature gives particles more kinetic energy, causing them to move faster. This increases both collision frequency AND the proportion of collisions with energy ≥ activation energy, significantly speeding up the reaction.
Higher concentration means more reactant particles per unit volume. This increases the likelihood of collisions occurring, resulting in a faster reaction rate. The particles have higher average kinetic energy.
For solid reactants like marble chips, smaller particle size increases total surface area. More surface is exposed for collisions, allowing more of the solid to react simultaneously with the acid, increasing reaction rate.
A catalyst lowers the activation energy required for a reaction without being consumed. This means more collisions have sufficient energy to cause a reaction, increasing the reaction rate without changing the temperature.