Hess's Law


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Hess's Law

Postby Dakota_Campbell_1C » Fri Feb 08, 2019 1:00 am

When calculating the overall enthalpy, particularly with the bond enthalpy problems will the bond energies always be given to us and if not how do we calculate them?

Janice Park 1E
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Joined: Fri Sep 28, 2018 12:22 am

Re: Hess's Law

Postby Janice Park 1E » Fri Feb 08, 2019 2:13 am

Yes! The bond enthalpies will typically be given to us when solving for reaction enthalpy using bond enthalpies - I would be quite surprised if they were not. You just have to make sure you correctly add the bond enthalpies of all bonds broken and all bonds formed, respectively.
Also, Hess's Law is used in Hess's Method for solving for reaction enthalpies, not with bond enthalpies. We typically correlate it with the summation of different reaction equations.

Ray Huang 1G
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Joined: Fri Sep 28, 2018 12:20 am

Re: Hess's Law

Postby Ray Huang 1G » Fri Feb 08, 2019 9:00 am

The bond enthalpies should be given or else we can't really solve the problem.

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