Homework Question Ch. 8 #55, Hess's Law

Moderators: Chem_Mod, Chem_Admin

504650118
Posts: 11
Joined: Fri Sep 25, 2015 3:00 am

Homework Question Ch. 8 #55, Hess's Law

Postby 504650118 » Wed Jan 06, 2016 8:28 pm

Question states that from the given two standard reactions enthalpies, to calculate the reaction enthalpy for the production of metallic barium in the reaction (pic of question attached). I was having some difficulty with it, so I checked the solution and the aluminum metal standard reaction enthalpy equation is different from the textbook and solution manuel?

The textbook has 2 Al (s) + O2 (g) --> Al2O3 (s) Change in enthalpy -1676 kj
The solution manuel has 2 Al (s) + 3/2 O2 (g) --> Al2O3 (s) Change in enthalpy -1676 kj
Attachments
20160106_200509.jpg

004662171
Posts: 4
Joined: Fri Sep 25, 2015 3:00 am

Re: Homework Question Ch. 8 #55, Hess's Law

Postby 004662171 » Wed Jan 06, 2016 9:41 pm

I was having the same issue as you, and I'm assuming that the issue lies in the textbook. The only way to solve the problem is if you go with what is in the solutions manual, because when adding together the two formulas, the O2 will not cancel out unless you have 3/2 as a coefficient in front of it in the second given equation. Also, the second equation is not even balanced without the coefficient, so I would go with what the solutions manual says.

504650118
Posts: 11
Joined: Fri Sep 25, 2015 3:00 am

Re: Homework Question Ch. 8 #55, Hess's Law

Postby 504650118 » Wed Jan 06, 2016 9:48 pm

Yeah, I assumed the solution manuels' coefficients were correct. Thanks for your input!


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 5 guests