Hess's Law

Moderators: Chem_Mod, Chem_Admin

Posts: 113
Joined: Wed Sep 21, 2016 2:57 pm

Hess's Law

Postby Blake_Katsev_2E » Mon Jan 16, 2017 12:26 am

How do you know when to flip an equation or halve or double it?

Posts: 35
Joined: Sat Jul 09, 2016 3:00 am

Re: Hess's Law

Postby Armo_Derbarsegian_3K » Mon Jan 16, 2017 1:11 am

When you need to cancel things from both sides. You switch signs to flip it.

for example:

A+B->C dH=x
2C->2A+D dH=y

you would multiply the top one by 2 to get A and C to cancel.

Posts: 12
Joined: Sat Jul 09, 2016 3:00 am

Re: Hess's Law

Postby gohar_mkrtchyan_2J » Mon Jan 16, 2017 1:24 am

you should also know that when you reverse an equation, you have to reverse the sign on the enthalpy value too.

Posts: 24
Joined: Wed Sep 21, 2016 2:56 pm

Re: Hess's Law

Postby Cobie_Allen_1H » Mon Jan 16, 2017 12:56 pm

I still don't really get when we should flip the reaction? Could you explain that for me?


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 1 guest