Collision Theory Chemistry Example 3

Follow the full solution, then compare it with the other examples linked below.

Example 3

medium
Using collision theory, explain why a finely ground powder reacts faster than a large chunk of the same solid.

Solution

  1. 1
    Grinding a solid into powder greatly increases its surface area, exposing more particles to the other reactant.
  2. 2
    More exposed particles means more collisions per unit time between the solid and the other reactant, resulting in a faster reaction rate.

Answer

MoreĀ surfaceĀ areaĀ ā†’Ā moreĀ collisionsĀ ā†’Ā fasterĀ rate\text{More surface area ā†’ more collisions ā†’ faster rate}
Surface area affects reaction rate for heterogeneous reactions (reactions involving different phases). This principle is why coal dust in mines can explode ā€” the enormous surface area allows extremely rapid combustion.

About Collision Theory

A model explaining that chemical reactions occur only when reactant particles collide with sufficient kinetic energy (at least equal to the activation energy) and in.

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More Collision Theory Examples

Example 1 easy

State the three conditions required for a successful chemical reaction according to collision theory

Example 2 medium

Use collision theory to explain why increasing the concentration of reactants increases the reaction

Example 4 hard

Two reactions have the same activation energy, but Reaction A involves small, linear molecules while

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