Chapter U5.104, Problem 1TAI

Interpretation Introduction

Interpretation: The source from which energy comes in an exothermic reaction needs to be explained.

Concept introduction: The total bond energy can be defined as the summation of individual bond energies of the bonds in the molecule.

If the energy value is positive, then the reaction is an endothermic reaction and if the energy value is negative, the reaction is an exothermic reaction.

Answer to Problem 1TAI

The energy in an exothermic reaction comes from the new form which is formed in the reaction.

Explanation of Solution

When a particular reaction takes place, the bonds between atoms gets broken and then new bonds forms. In order to break a bond, energy must be transferred. This energy which is needed to break a bond is termed as the bond energy.

When a new bond forms, some amount of energy is released. The heat which is transferred in a chemical reaction is equal to the difference in the energy between the bond-breaking process and that of the bond-making process.

Conclusion

When a new bond forms, some amount of energy is released. This is where the energy of an exothermic reaction comes from.