Chemistry 12th Edition

Published by McGraw-Hill Education
ISBN 10: 0078021510
ISBN 13: 978-0-07802-151-0

Chapter 9 - Chemical Bonding I - Questions & Problems: 9.68

Answer

Please see the work below.

Work Step by Step

We know that bond enthalpy is measured fro atoms in gaseous state because there are only coalent bonds between the atoms and hence the measurement becomes accurate. For a bond to be broken, energy is required and hence it is endothermic while to form a bond, energy is released and hence the reaction is exothermic.
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