which bonds to break/form  [ENDORSED]

Moderators: Chem_Mod, Chem_Admin

haleh matinrad 1C
Posts: 17
Joined: Sat Jul 09, 2016 3:00 am

which bonds to break/form

Postby haleh matinrad 1C » Thu Jan 19, 2017 2:21 pm

When using bond enthalpies to calculate the standard enthalpy of reaction, can you calculate breaking and forming all bonds in the equation? I know this would take an excessively long time but would you get the same result doing this as you would breaking and forming the minimum number of bonds required for the equation to take place? Also, is it just a matter of practice in learning which bonds to break and form?

Aneesh_Gowri 1H
Posts: 21
Joined: Wed Sep 21, 2016 2:59 pm

Re: which bonds to break/form  [ENDORSED]

Postby Aneesh_Gowri 1H » Thu Jan 19, 2017 5:20 pm

Hi! I'm pretty sure you will get the same answer if you calculate every bond that breaks and forms, it will just take a bit longer to get the answer. However, your answer should still be correct, you just have to make sure to write all the bonds out to make sure you include all the necessary information.

Mannat Sukhija 1E
Posts: 23
Joined: Fri Jul 22, 2016 3:00 am

Re: which bonds to break/form

Postby Mannat Sukhija 1E » Sat Jan 21, 2017 1:48 pm

To answer the second part of the question on how you know which bonds to break and form, when using bold enthalpies you can take the opposite of the enthalpy of formation of all of the reactants and add this to the enthalpy of formation of the products. This is because breaking bonds in the reactants requires energy, and forming the bonds from those same reactants to make the products releases energy.

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

Who is online

Users browsing this forum: No registered users and 2 guests