Suppose reaction A involves the making of bonds and 22.5 J of energy, reaction B involves the breaking of bonds and 40.0 J of energy, and reaction C involves the making of bonds and 125.0 J of energy
What is the overall A + B + C reaction energy? Is this an exothermic or an endothermic reaction? Explain.
In making bonds, the total energy release was 22.5 J + 125 J = 147.5 J. This is
more than the energy supplied to break bonds, 40.0 J. Overall in this reaction, bonds are
made and net energy is supplied by the chemical system to the outside. This is an
exothermic reaction, because energy of 107.5 J [= 147.5 J - 40.0 J] can be extracted from
the system when the reaction occurs.
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