Bond Enthalpies

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Katelyn 2E
Posts: 35
Joined: Sat Jul 22, 2017 3:01 am

Bond Enthalpies

Postby Katelyn 2E » Wed Jan 10, 2018 11:13 pm

Can someone please explain to me why bond enthalpies (method 2) are always positive? Thank you!

Emma Li 2C
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Re: Bond Enthalpies

Postby Emma Li 2C » Wed Jan 10, 2018 11:28 pm

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

Alvin Tran 2E
Posts: 39
Joined: Fri Sep 29, 2017 7:06 am

Re: Bond Enthalpies

Postby Alvin Tran 2E » Wed Jan 10, 2018 11:30 pm

Also, the products side is negative because energy is released when new bonds are formed.

Anne 2L
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Joined: Fri Sep 29, 2017 7:05 am

Re: Bond Enthalpies

Postby Anne 2L » Wed Jan 10, 2018 11:35 pm

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.

Anne 2L
Posts: 35
Joined: Fri Sep 29, 2017 7:05 am

Re: Bond Enthalpies

Postby Anne 2L » Wed Jan 10, 2018 11:36 pm

OH WOW YOU GUYS TYPE FAST.

Dang Lam
Posts: 55
Joined: Thu Jul 27, 2017 3:01 am

Re: Bond Enthalpies

Postby Dang Lam » Wed Jan 10, 2018 11:52 pm

Because you are breaking the bonds, meaning energy is required and that mean positive value

Nicole Jacobs 1C
Posts: 59
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Re: Bond Enthalpies

Postby Nicole Jacobs 1C » Thu Jan 11, 2018 8:16 am

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.


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