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Bond Enthalpies

Posted: Thu Feb 06, 2020 2:14 am
by Giselle Littleton 1F
I notice that in some problems from the homework, specific bonds within molecules aren't included when calculating the bond enthalpies. Why is that and how can I watch out for those that I should not include?

Re: Bond Enthalpies

Posted: Thu Feb 06, 2020 2:51 pm
by sarahsalama2E
I'm not sure if this is exactly what you are referring to but molecules in their most stable state, aka H2, 02 do not have bond enthalpies because they are in their most stable state, because it takes no energy to form a naturally-occuring compound that wants to be formed.

Re: Bond Enthalpies

Posted: Fri Feb 07, 2020 12:25 am
by Shrayes Raman
I may be misunderstanding your question however you do not need to include bond enthalpies for bonds that are not broken in a reaction, ie 3C2H2 -> C6H6 do not need H - C bond enthalpies because they are not broken

Re: Bond Enthalpies

Posted: Sat Feb 08, 2020 4:41 pm
by Maika Ngoie 1B
Normally bond enthalpies should be stated, unless it is the most stable form of the naturally occurring element, in which case it does not have a bond enthalpy.

Re: Bond Enthalpies

Posted: Sat Feb 08, 2020 5:27 pm
by Micah3J
If on a test we were asked to use Hess's law, we would be given a table that shows the bond enthalpies right? If anything I just need to remember which ones are 0.