When a chemical reaction occurs, it requires a certain amount of energy to get started, known as the activation energy. This activation energy can vary depending on the presence or absence of a catalyst. A catalyst is a substance that increases the rate of a chemical reaction without itself undergoing any permanent chemical change, and it typically works by lowering the activation energy needed for the reaction.
Given the initial activation energy of the reaction without a catalyst is 20 kJ:
1. Identify the effect of a catalyst: A catalyst lowers the activation energy required for a reaction.
2. Analyze the options given:
- 15 kJ
- 20 kJ
- 25 kJ
- 30 kJ
3. Choose the most likely option that represents the activation energy with a catalyst:
- Since catalysts lower the activation energy, the value must be less than the initial activation energy of 20 kJ.
From the options provided, the only value less than 20 kJ is:
- 15 kJ
Thus, with the presence of a catalyst, the most likely value that represents the amount of energy needed to start the reaction is 15 kJ.
