What is bond enthalpy and can someone explain to me what Lavelle was doing with the Lewis Structures in today's lecture?

Moderators: Chem_Mod, Chem_Admin

Adriana Rangel 1A
Posts: 96
Joined: Fri Sep 29, 2017 7:04 am

What is bond enthalpy and can someone explain to me what Lavelle was doing with the Lewis Structures in today's lecture?

Postby Adriana Rangel 1A » Wed Jan 10, 2018 5:16 pm

Hello, I do not understand what Lavelle was doing with the Lewis structures and bond enthalpy in class today (1/10) . Could someone please explain ?

Daniisaacson2F
Posts: 30
Joined: Sat Jul 22, 2017 3:00 am

Re: What is bond enthalpy and can someone explain to me what Lavelle was doing with the Lewis Structures in today's lect

Postby Daniisaacson2F » Wed Jan 10, 2018 5:32 pm

Bond enthalpy is the energy needed to break a bond. In today's lecture, Lavelle was essentially trying to show us which bonds are broken in the specific reaction, and how you use the enthalpies from both the reactants and products to find the total change in enthalpy. Since there were bonds broken and "rearranged", you can use the information that they give you about the enthalpies from each specific bond to find the change once the reaction is complete.

Tiffany 1B
Posts: 32
Joined: Fri Sep 29, 2017 7:05 am

Re: What is bond enthalpy and can someone explain to me what Lavelle was doing with the Lewis Structures in today's lect

Postby Tiffany 1B » Wed Jan 10, 2018 6:14 pm

Yeah exactly what Daniisaacson2F was saying. Using the bond enthalpies was just an alternative to the first method w/ Hess's Law. The bonds that were broken were the C=C bond and the H-Br bond and the ones formed/ rearranged were the C-C, C-H, C-Br bonds. Then he used the bond enthalpy values(knowing that bonds broken require energy so + and those broken release energy so -) to find the overall net change.

Julianna Thrasher 1B
Posts: 27
Joined: Thu Jul 27, 2017 3:00 am

Re: What is bond enthalpy and can someone explain to me what Lavelle was doing with the Lewis Structures in today's lect

Postby Julianna Thrasher 1B » Fri Jan 12, 2018 12:44 pm

When Professor Lavelle drew out the Lewis structures he was just visually explaining which bonds will be broken in the reactants in order to form new bonds for the products. You only use the bond energies of the bonds broken and formed in order to calculate bond enthalpy, and it may be tricky sometimes to just guess which ones are included so Lavelle drew them out.


Return to “Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)”

Who is online

Users browsing this forum: Google [Bot] and 2 guests