according to the enthalpy diagram below, which of the following statements is true?\n\narrows a and d…
according to the enthalpy diagram below, which of the following statements is true?\n\narrows a and d represent the enthalpy of the intermediate chemical reactions.\narrow c represents the enthalpy of the overall chemical reaction.\narrow c indicates that the third intermediate reaction is exothermic.\narrow b indicates that the second intermediate reaction is exothermic.
Answer
Explanation:
Step1: Recall enthalpy - reaction concepts
Enthalpy change ($\Delta H$) is positive for endothermic reactions (heat absorbed) and negative for exothermic reactions (heat released). The overall $\Delta H_{rxn}$ is related to the sum of $\Delta H$ values of intermediate reactions in a multi - step reaction.
Step2: Analyze each option
- Option 1: Arrows A and D do not represent the enthalpy of intermediate chemical reactions in the correct sense. Intermediate reactions are usually steps in a multi - step reaction mechanism, and this description is incorrect.
- Option 2: Arrow C does not represent the enthalpy of the overall chemical reaction. The overall $\Delta H_{rxn}$ is usually related to the difference between the final and initial states.
- Option 3: Arrow C points downwards, which means $\Delta H_3<0$. A negative $\Delta H$ value indicates an exothermic reaction. So, arrow C indicates that the third intermediate reaction is exothermic. This is correct.
- Option 4: Arrow B points upwards, so $\Delta H_2 > 0$, which indicates an endothermic reaction, not an exothermic one.
Answer:
Arrow C indicates that the third intermediate reaction is exothermic.