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Bond Enthalpy

Posted: Thu Jan 14, 2016 9:01 pm
by Arlene Paramo 1I
When to do you make the standard reaction enthalpy negative? Is it when you're breaking or forming a bond and why does it need to be negative?

Re: Bond Enthalpy

Posted: Thu Jan 14, 2016 9:06 pm
by Matthew Gutierrez 2D
You make the bond enthalpy negative when you are forming a bond. It is negative because forming a bond is exothermic because the molecule becomes more stable and releases energy.

Re: Bond Enthalpy

Posted: Sat Jan 16, 2016 6:23 pm
by Gabriel Esmailian 1F
In order to break a bond, energy is needed. This uptake in energy constitutes a positive enthalpy value. On the other hand, to make bonds energy is release, and thus enthalpy value will be negative because energy is leaving the system.