# Z in diagram above represents…

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## Z in diagram above represents

A. heat of reaction

B. activation energy

C. free energy

D. entropy of reaction

A

## DETAILS…

Heat of reaction is the difference between the enthalpy of formation of products and the enthalpy of reactants.

That is, heat of reaction = heat of formation of products – heat of formation of reactants.

From the graph, we can see that the portion labeled Z represents the difference between the energy of products ( C + D), and that of reactants (A + B). So, Z represents the heat of reaction.

### Now for the right answer to the above question:

1. Option A is correct.
2. Option B is incorrect. Activation energy is the energy limit of a reaction which must be supplied in order to start the reaction, from the diagram, it is represented by (Y + Z)
3. C is incorrect. please note that the vertical axis is not plotted in Gibbs free energy, but in energy state, hence, Z can be seen as heat of reaction.
4. D is not the correct answer. Entropy is the degree of disorderliness of a reaction, it is not shown in the graph.