Activation Energy Chemistry Example 2

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Example 2

medium
On an energy diagram, Reaction A has Ea=50 kJ/molE_a = 50\,\text{kJ/mol} and Reaction B has Ea=120 kJ/molE_a = 120\,\text{kJ/mol}. Both occur at the same temperature. Which reaction is faster and why?

Solution

  1. 1
    A lower activation energy means more molecules have sufficient energy to react at a given temperature.
  2. 2
    Reaction A (Ea=50 kJ/molE_a = 50\,\text{kJ/mol}) has a lower barrier than Reaction B (120 kJ/mol120\,\text{kJ/mol}).
  3. 3
    Therefore, Reaction A proceeds faster at the same temperature.

Answer

Reaction A is faster (lower Ea)\text{Reaction A is faster (lower } E_a\text{)}
The activation energy determines the fraction of collisions that are energetic enough to lead to products. Lower EaE_a means a greater fraction of successful collisions and a faster reaction rate.

About Activation Energy

The minimum kinetic energy that reactant particles must possess upon collision in order to break existing bonds and initiate a chemical reaction, represented as the.

Learn more about Activation Energy →

More Activation Energy Examples

Example 1 easy

Explain why a match must be struck before it ignites, even though combustion is exothermic.

Example 3 easy

Does a catalyst change the activation energy of a reaction? How?

Example 4 medium

Paper burns exothermically, but a sheet of paper can sit at room temperature for days without catchi

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