# Thermodynamic Cycle

What is the value for $\Delta_f G^0(\ce{Cl^-}, \ce{aq})$ in this thermodynamic cylce:

Do you agree it should be (with the formation free energy of $\ce{H^+} = 0$)

$$-\Delta_f G^0(\ce{Cl^-}, \ce{aq}) + 218 + 1312 + 106 = 349 - \Delta_{Solv}G^0(\ce{Cl^-}) - \Delta_{Solv}G^0(\ce{H^+})$$

and so

$$\Delta_fG^0(\ce{Cl^-}, \ce{aq}) = 1287 + \Delta_{Solv}G^0(\ce{Cl^-}) + \Delta_{Solv}G^0(\ce{H^+})$$

(values in kJ/mol). My book however writes 1272 kJ/mol.

What is wrong?

• What are the specific concepts you're having trouble with? Please do bear in mind this FAQ on meta: "It's not enough to just show your work and ask where you went wrong. If you just need someone to check your work, you can always seek out a friend, classmate, or teacher" – EnergyNumbers Apr 30 '13 at 13:30
• The specific concept I'm having trouble with is, as I have found out, is that the book wrote a wrong value for the result (in editions 7 and 8) and the value I get is correct (in "Quanta, Matter, Change"). – TMOTTM Apr 30 '13 at 15:19
• @TMOTTM - If your answer is correct (and the book is wrong), answer your own question with some detail about your answer. as the faq says, you are permitted to answer your own question. – Ben Norris May 1 '13 at 11:26

## 1 Answer

The book is wrong. The answer written in the original post is correct.