(h) If a catalyst was added to the reaction, which quantities would change? (Select all that apply.)
- the potential energy of the products
- the potential energy of the reactants
- the potential energy of the activated complex
-the activation energy for the reverse reaction
- the activation energy for the forward reaction
I know catalysts lower the activation energy, so I think the last two would change. Do more quantities change?
I tried to find some graphs; here is the best I could do.http://en.wikipedia.org/wiki/Reaction_coordinate
You're right with your statement about catalysts and I agree that the last two change. I am ambivalent about c because of the wording. Adding a catalyst certainly lowers the activation energy and that complex has a lower potential energy than the uncatalyzed reaction which would tend to make me choose c also. However, before the catalyst is added THERE IS NO activated complex and it will move to whatever level the reaction takes it but it will not change from some pre-determined level. That makes me not choose c. So take your pick. I'm inclined to think c is worded that way as a trick part of the question and I would not choose it.
You are correct that catalysts lower the activation energy. Therefore, the quantities that would change if a catalyst was added to the reaction are:
- The activation energy for the reverse reaction
- The activation energy for the forward reaction
Excellent start! You're right that catalysts lower the activation energy, but there are also some other changes that occur when a catalyst is added to a reaction. Let's go through each option to see which quantities would change:
1. The potential energy of the products: Adding a catalyst does not directly affect the potential energy of the products since it only impacts the rate of the reaction, not the overall energy of the products.
2. The potential energy of the reactants: Similar to the previous point, adding a catalyst does not directly alter the potential energy of the reactants. The catalyst only provides an alternate reaction pathway, affecting the rate but not the overall energy.
3. The potential energy of the activated complex: The activated complex refers to the high-energy intermediate state that occurs during a chemical reaction. When a catalyst is added, it provides an alternate reaction pathway with a lower activation energy, which means that the potential energy of the activated complex is reduced.
4. The activation energy for the reverse reaction: This one is correct! Adding a catalyst would also lower the activation energy for the reverse reaction, facilitating the formation of the reactants from the products.
5. The activation energy for the forward reaction: You are correct again! A catalyst would lower the activation energy for the forward reaction, making it easier for the reactants to form products.
So, to summarize, when a catalyst is added to a reaction, the quantities that would change are the potential energy of the activated complex, the activation energy for the reverse reaction, and the activation energy for the forward reaction.