Answer
Activation Energy and Rate Constant Explained
Explore how energy profile diagrams help determine reaction speed using the Arrhenius equation.
1. What is an Energy Profile?
An energy profile diagram illustrates the energy changes during a chemical reaction. It tracks the transformation of reactants into products through an energy pathway.
- Reactants and Products: Their relative energies are shown.
- Activation Energy (Ea): The energy needed to initiate the reaction.
Activation energy is the minimum energy required for a successful collision that leads to a reaction.
2. Arrhenius Equation and Rate Constant
The Arrhenius equation explains how the rate constant (K) is influenced by activation energy and temperature:
- K: Rate constant
- A: Frequency or pre-exponential factor
- Ea: Activation energy (J/mol)
- R: Universal gas constant
- T: Temperature (Kelvin)
When Ea decreases, the exponential term increases, and the rate constant becomes larger.
3. Which Energy Profile Has the Highest Rate Constant?
Based on the diagrams provided, Profile C has the lowest activation energy.
This means more molecules can overcome the energy barrier, leading to a faster reaction.
Thus, Profile C corresponds to the highest rate constant among all options.
4. Final Conclusion
Energy profiles with lower activation energy allow more molecules to react, resulting in a higher rate constant. In this case, Option C has the largest rate constant because it has the lowest energy barrier.