Answer
🧪 Effect of Various Changes on Reaction Rate
Understanding the Rate Law
The general rate law is:
Rate = k[A]^m[B]^nWhere:
- A and B are reactants
- m and n are the orders of reaction
- k is the rate constant, influenced by temperature
Effects on Reaction Rate
1. Increase the concentration of a reactant in the rate law
✔ Will increase the rate of the reaction
Explanation: If the reactant appears in the rate law with a positive order, increasing its concentration increases the reaction rate.
2. Increase the concentration of a species not in the rate law
➖ Will have no effect on the rate of the reaction
Explanation: If a species does not appear in the rate law (i.e., zero-order), changing its concentration will not affect the rate.
3. Lowering the temperature
✖ Will decrease the rate of the reaction
Explanation: Lower temperature reduces kinetic energy, resulting in fewer effective collisions.
4. Lowering activation energy via alternate pathway (e.g., catalyst)
✔ Will increase the rate of the reaction
Explanation: A catalyst provides a path with lower activation energy, making it easier for reactants to form products.
📘 Summary Table
| Change | Effect on Rate |
|---|---|
| Increase concentration of a reactant in the rate law | Increases rate |
| Increase concentration of a species not in the rate law | No effect on rate |
| Lower the temperature | Decreases rate |
| Lower the activation energy (e.g., using a catalyst) | Increases rate |