Questions 44-46 relate to the following information. XY2 → X + Y2 The equation above represents the — Kinetics Chemistry Question

STEPS:

1. Analyze the visual information in the potential energy diagram (reaction profile):
* Both reaction profiles start at the same initial potential energy level (representing the reactant, $\text{XY}_2$) and end at the same final potential energy level (representing the products, $\text{X} + \text{Y}_2$).
* The enthalpy of reaction ($\Delta H$), which is the difference in energy between products and reactants, is identical for both paths (both depict an endothermic reaction with $\Delta H = +50\text{ kJ/mol}_{rxn}$).
* The only difference between the two curves is the height of the energy barrier from the reactants to the peak of the curve, which represents the activation energy ($E_a$):
* Path One has a higher activation energy barrier of $150\text{ kJ/mol}_{rxn}$.
* Path Two has a lower activation energy barrier of $100\text{ kJ/mol}_{rxn}$.
2. Recall the chemical function of a catalyst:
* A catalyst is a substance that increases the rate of a chemical reaction without being consumed in the process.
* It achieves this by providing an alternative reaction pathway (mechanism) that has a lower activation energy than the uncatalyzed pathway.
* By lowering the activation energy barrier, a larger fraction of colliding reactant molecules possess the necessary minimum energy to react at a given temperature, which increases the reaction rate.
* Crucially, a catalyst does not alter the thermodynamic energies of the reactants or products, meaning the net reaction enthalpy ($\Delta H$) is unchanged.
3. Connect the catalyst's behavior to the paths:
* Since Path Two shows a lowered activation energy peak compared to Path One while maintaining the exact same reactant and product energy levels, Path Two represents the catalyzed reaction pathway and Path One represents the uncatalyzed reaction pathway.
* Thus, the difference between the two paths is accounted for by the presence of a catalyst in path two, which corresponds to Option D.

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WHY_OTHERS_WRONG:

• Options A and B are incorrect: Temperature is a measure of the average kinetic energy of the reacting particles. Changing the temperature changes how fast molecules move and how energetically they collide, but temperature does not alter the potential energy curve or the activation energy barrier of a reaction pathway. The potential energy profiles and their peaks remain identical regardless of whether the temperature is high or low.
• Option C is incorrect: This option asserts that a catalyst is present in Path One. However, Path One has the higher activation energy peak ($150\text{ kJ/mol}_{rxn}$), which represents the uncatalyzed, higher-energy route. Because a catalyst must lower the activation energy barrier, it is present in Path Two rather than Path One.