O-Chem Textbook

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O-Chem Textbook

Postby Shark » Fri Mar 17, 2017 11:51 am

Quick technical question. On Pg 108 of the OChem textbook it discusses the relative energy difference between the eclipsed and anti-conformation of butane being -120 kj/mol. the 2 pairs of C-H bonds accounts for +4 kj/mol. Thus, shouldnt the remainder (which accounts for the pair of eclipsed CH3) be +12 Kj/mol and not +11 kJ/mol? The textbook says +11 Kj/mol.

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Re: O-Chem Textbook

Postby Chem_Mod » Sat Mar 18, 2017 9:50 pm

You mean -20 kJ.mol-1 not -120.

Round off errors account for the difference.

For example, ~2 kcal x 4.18 kJ/kcal is ~8.36 kJ

If the calculations are done using more accurate values it works out to +11 kJ.

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