C-H Bond +4 kJ/mol

Camila Bautista 3I
Posts: 20
Joined: Fri Sep 25, 2015 3:00 am

C-H Bond +4 kJ/mol

Is the +4 a predetermined value? Or is there a way to calculate it? And what exactly does it indicate?
So for example, "The relative energy difference between the eclipsed and staggered conformations of ethane is approximately -12 kJ/mol. Since ethane's eclipsed conformation has three pairs of eclipsed C-H bonds we can estimate that each unfavorable interaction per pair of eclipsed C-H bonds is +4 kJ/mol."

Was the -12 kJ/mol a predetermined value?

Kurtis Lavelle 1k
Posts: 10
Joined: Fri Sep 25, 2015 3:00 am

Re: C-H Bond +4 kJ/mol

The -12 kJ is the given value. Since we know that there are three eclipsed bonds, we divide by three to get the 4kJ value. The 4kJ value indicates the extra energy it takes to form this conformation.

Nikhita_Jaaswal_2H
Posts: 31
Joined: Wed Sep 21, 2016 2:57 pm

Re: C-H Bond +4 kJ/mol

This value is calculated and is constant for all the C-H bonds

Narin Maisha 2H
Posts: 100
Joined: Fri Sep 24, 2021 6:49 am

Re: C-H Bond +4 kJ/mol

The -12kJ is a predetermined value and the value +4kJ/mol is a calculated value found later.

marcelnajjar
Posts: 84
Joined: Fri Sep 29, 2023 10:44 am

Re: C-H Bond +4 kJ/mol

Camila Bautista 3I wrote:Is the +4 a predetermined value? Or is there a way to calculate it? And what exactly does it indicate?
So for example, "The relative energy difference between the eclipsed and staggered conformations of ethane is approximately -12 kJ/mol. Since ethane's eclipsed conformation has three pairs of eclipsed C-H bonds we can estimate that each unfavorable interaction per pair of eclipsed C-H bonds is +4 kJ/mol."

Was the -12 kJ/mol a predetermined value?

Yes it is predetermined and a constant value for bonds