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Question Video: Determining What Is Not True about a Catalyzed Reaction Chemistry • 7th Grade

Considering the diagram, which of the following statements is not true of a catalyzed reaction? [A] Fewer particles have sufficient energy to react. [B] The catalyst provides an alternative reaction pathway. [C] The catalyst is not consumed during the reaction. [D] The activation energy is smaller. [E] The overall energy change is the same.

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Video Transcript

Considering the diagram, which of the following statements is not true of a catalyzed reaction? (A) Fewer particles have sufficient energy to react. (B) The catalyst provides an alternative reaction pathway. (C) The catalyst is not consumed during the reaction. (D) The activation energy is smaller. Or (E) the overall energy change is the same.

Here we are looking to discern which statement is not a correct statement for catalysis reactions. Scientists use collision theory to understand how reactants turn to products and at what rate. Collision theory states that reactant particles will turn into products when they collide with enough energy to overcome the energy barrier called the activation energy. The activation energy is defined as the minimum amount of energy required for a reaction to occur.

When the activation energy of a given reaction is high, such as the pink line in the diagram, then conversion to product is low. Conversely, when the activation energy is low, such as in the dotted red line, conversion to product is high because it requires less energy to overcome the barrier.

When activation energies become very high, it’s common to use catalysts. A catalyst is a substance that increases the rate of a reaction without undergoing a permanent chemical change. The result is that a catalyst lowers the activation energy, allowing the reaction to proceed more easily via a new reaction pathway. It’s important to note that in both the catalyzed and noncatalyzed reaction pathways, the overall energy change, or Δ𝐻 of the reaction, is the same.

And with this information, we can revisit and answer the question. Considering the diagram, which of the following statements is not true of a catalyzed reaction? And the correct answer is (A): fewer particles have sufficient energy to react.

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