Breaking all four carbon to hydrogen bonds in one mole of methane takes 1660 kJ. What is the average bond energy?

1. The 1660 kilojoules pays for four moles of carbon to hydrogen bonds, not one. 2. An average per bond therefore divides the total by the number of bonds. 3. That is 1660 kilojoules divided by 4, which is 415 kilojoules per mole. 4. The four bonds are equivalent in the intact molecule, but they do not each cost the same to break. 5. The first bond alone takes 439 kilojoules per mole, and the rest come off more easily. 6. So 439 kilojoules per mole is the first bond, not the average, and it is the trap here. 7. 830 kilojoules per mole is the total halved, which would only be right for two bonds. 8. 1660 kilojoules per mole is the whole molecule and ignores the division altogether. _Source: OpenStax Chemistry (CC BY 4.0), Chs 7 and 17, section 7.5 Strengths of Ionic and Covalent Bonds_