Hess' Law Confirmation

Moderators: Chem_Mod, Chem_Admin

Alexandria Ilagan 2A
Posts: 19
Joined: Fri Sep 28, 2018 12:22 am

Hess' Law Confirmation

Postby Alexandria Ilagan 2A » Sat Jan 26, 2019 7:45 pm

Just to confirm about Hess' Law, to calculate the total change in heat, we add the balanced equations and change of heat of both reactions?

Chloe Likwong 2K
Posts: 70
Joined: Fri Sep 28, 2018 12:23 am

Re: Hess' Law Confirmation

Postby Chloe Likwong 2K » Sat Jan 26, 2019 7:56 pm

You would cancel the reactants and products if they're on opposite sides of the equation. Make sure to remember that it should be in the same state.

You might have to multiply or reverse the reaction in order to cancel some reactants/products. If you multiply, you should also do the same to the enthalpy. If you reverse the reaction, make sure to switch the signs (e.g. if it's an endothermic rxn and you reverse it, it will become exothermic; from [+] to [-]).

Hope this helps!

Aidan Ryan 1B
Posts: 60
Joined: Fri Sep 28, 2018 12:17 am

Re: Hess' Law Confirmation

Postby Aidan Ryan 1B » Sat Jan 26, 2019 8:18 pm

If you do the stuff described about combining two equations and canceling out are you able to write 1 equation with all of this and denote this someway?

Jaira_Murphy_2D
Posts: 31
Joined: Fri Apr 06, 2018 3:00 am

Re: Hess' Law Confirmation

Postby Jaira_Murphy_2D » Sun Jan 27, 2019 1:49 pm

Can someone explain how I know which equation to start with for Hess' Law?


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