Reactants have a higher enthelpy

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In an exothermic reaction, the reactants possess higher enthalpy compared to the products, as illustrated in energy profile diagrams. This indicates that the products have lower enthalpy. However, the bond enthalpy differs; reactants have lower bond enthalpy, requiring less energy to break their bonds, while products have higher bond enthalpy, releasing more energy when new bonds are formed. This distinction clarifies that enthalpy and bond enthalpy are not the same. During the reaction, internal energy and enthalpy fluctuate, initially increasing to a peak known as Activation Energy before decreasing. It is important to note that even exothermic reactions, like combustion, require an initial energy input to initiate the process, highlighting that reactions do not occur in a straightforward manner.
GeneralOJB
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Am I right in saying that, in an exothermic reaction for example, the reactants have a higher enthalpy, and the products have a lower enthalpy, as seen from the energy profile diagram.
But the reactants have a lower bond enthalpy, and the products have a higher bond enthalpy, because a lower amount of energy is required to break the bonds in the reactants, but a higher amount of energy is released when the new bonds are formed. This just confused me as I thought enthalpy and bond enthalpy were the same thing!
 
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During the course of reaction, the internal energy, and by extension, enthalpy, changes.

For e.g. During a reaction, the energy first increases to a certain maximum level (Difference in energy is called Activation Energy) then it comes down. (You know the bell-shaped graph)

The reactions doesn't takes place in arithmetic method. Even if burning is exothermic, it doesn't mean that we do not have to provide energy to do it.
 

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