What does a positive ΔH look like on a potential energy diagram?
A. The potential energy of the products is equal to the potential energy of the reactants.
B. The potential energy of the reactants is greater than the potential energy of the products.
C. The activation energy of the reactants is less than the activation energy of the products.
D. The potential energy of the products is greater than the potential energy of the reactants.
Answer (2)
A positive ΔH signifies an endothermic reaction.
In a potential energy diagram, the y-axis represents potential energy.
A positive ΔH means the potential energy of the products is greater than the potential energy of the reactants.
Therefore, the correct answer is D: The potential energy of the products is greater than the potential energy of the reactants. D
Explanation
Understanding the Problem A positive ΔH (enthalpy change) indicates an endothermic reaction, meaning the reaction absorbs heat from its surroundings. In a potential energy diagram, the y-axis represents potential energy, and the x-axis represents the reaction coordinate, which is a measure of the progress of the reaction. The potential energy of the reactants and products are represented on the y-axis. ΔH is the difference between the potential energy of the products and the potential energy of the reactants:
Relating ΔH to Potential Energy Since Δ H = Potential Energy (products) − Potential Energy (reactants) , a positive ΔH means that \text{Potential Energy (reactants)}"> Potential Energy (products) > Potential Energy (reactants) . Therefore, on a potential energy diagram, the products will have a higher potential energy than the reactants.
Conclusion Based on the analysis, the correct answer is: D. The potential energy of the products is greater than the potential energy of the reactants.
Examples
Consider a chemical reaction where you're baking a cake. If the reaction is endothermic (positive ΔH), it means the cake batter needs to absorb energy (heat) from the oven to transform into a cake. On a potential energy diagram, this would be represented by the cake (products) having a higher potential energy than the initial batter (reactants). This visualization helps understand why some reactions require energy input to proceed.
A positive ΔH indicates that the reaction is endothermic, meaning it absorbs energy. In a potential energy diagram, this is shown by the potential energy of the products being greater than that of the reactants. Thus, the correct choice is D: The potential energy of the products is greater than the potential energy of the reactants.
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