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Bond Enthalpies

Posted: Wed Jan 10, 2018 11:13 pm
by Katelyn 2E
Can someone please explain to me why bond enthalpies (method 2) are always positive? Thank you!

Re: Bond Enthalpies

Posted: Wed Jan 10, 2018 11:28 pm
by Emma Li 2C
Energy is required to break a bond! Like in an endothermic reaction, energy is inputed and so the energy required to break the bonds is positive

Re: Bond Enthalpies

Posted: Wed Jan 10, 2018 11:30 pm
by Alvin Tran 2E
Also, the products side is negative because energy is released when new bonds are formed.

Re: Bond Enthalpies

Posted: Wed Jan 10, 2018 11:35 pm
by Anne 2L
Katelyn 2E wrote:Can someone please explain to me why bond enthalpies (method 2) are always positive? Thank you!


Yea np I gotchu girl! In method 2, the bond enthalpy values given are always positive, because the value given represents the amount of kJ/mol required to break the bond. Since breaking the bond requires energy, the process is endothermic and therefore the enthalpy value is positive.

Re: Bond Enthalpies

Posted: Wed Jan 10, 2018 11:36 pm
by Anne 2L
OH WOW YOU GUYS TYPE FAST.

Re: Bond Enthalpies

Posted: Wed Jan 10, 2018 11:52 pm
by Dang Lam
Because you are breaking the bonds, meaning energy is required and that mean positive value

Re: Bond Enthalpies

Posted: Thu Jan 11, 2018 8:16 am
by Nicole Jacobs 1C
And vice versa, if you were to add bonds, the reaction would be exothermic because energy is released when bonds are formed. Thus it would be negative if you were talking about the opposite.