Question

unit test #3
question 16 (1 point)
examine the figure below for the following question:
which letter represents the enthalpy change of the reaction?
a
b
c
d
none of the above

Explanation:

Enthalpy change ($\Delta H$) of a reaction is the difference between the potential energy of products and reactants. In a potential - energy diagram, it is represented by the vertical difference between the energy level of products and reactants.

• Option A: This represents the activation energy (the energy barrier that needs to be overcome for the reaction to start), not the enthalpy change.
• Option B: This is not a standard representation in terms of enthalpy change or activation energy in a simple reaction - progress diagram.
• Option C: This correctly represents the difference in potential energy between products and reactants, which is the definition of enthalpy change ($\Delta H=E_{products}-E_{reactants}$).
• Option D: This represents the total energy of the activated complex (the highest - energy point in the reaction), not the enthalpy change.

Answer:

C.