Use the graph to answer these questions. For
numerical answers, use correct significant digits.
Letter
shows the overall enthalpy of reaction
which is equal to
kJ.
shows the activation energy for the
Letter
reaction.
The activated complex is represented by

Enthalpy of reaction is described below.

Explanation:

During chemical reactions, the bonds between atoms may break, reform or both to either absorb or release energy. The result is a change to the potential energy of the system. The heat absorbed or released from a system under constant pressure is known as enthalpy, and the change in enthalpy that results from a chemical reaction is the enthalpy of reaction. The enthalpy of reaction is often written as ΔΗrₓₙ

To better understand enthalpy of reaction, let's consider the hydrogenation of propene, C₃H₆ , to form propane, C₃ H₈.in this reaction first we have to break the carbon C=C  bond and the hydrogen H- H bond of the reactants. As a rule, breaking bonds between atoms requires adding energy. The stronger the bond, the more energy it takes to break the bond. To make the product propane, a new C-C  bond and two new C-H bonds are then formed. Since breaking bonds requires adding energy, the opposite process of forming new bonds always releases energy. The stronger the bond formed, the more energy is released during the bond formation process. In this particular reaction, because the newly formed bonds release more energy than was needed to break the original bonds, the resulting system has a lower potential energy than the reactants. This means the enthalpy of reaction is negative.

the enthalpy of reaction as the difference between the potential energy from the product bonds and the potential energy of the reactant bonds:

ΔΗrₓₙ

=potential energy of product bonds−potential energy of reactant bonds

=energy added to break reactant bonds+energy released when making product bonds

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hope that