Talk:Van 't Hoff equation

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[edit] Pressure

Hrm. So I was in chemistry and i was thinking. Pressure changes should affect things exactly the same way as temperature changes...so does a equation like the van't hoff equation exist for pressure changes as well? (in gases only, i'm guessing)

our professor tells us to use PV=nRT to calculate, assuming Kc is the same for both pressures. However, I can't see how this is possible!

Strangely enough, RICHARD C. TOLMAN; “Equilibria in dispersed systems and the thermodynamic theory of theory of colloids”; Journal of the American Chemical Society; American Chemical Society; April 1913; 35 (4): pp. 317–333. actually refers to "PV=nRT" as "the law of van't Hoff".

—DIV (128.250.80.15 (talk) 06:11, 31 March 2008 (UTC))

The equilibrium constant K does not depend on pressure !

Since it's defined at equilibrium where DG = 0, we have

DG = DGo + R.T.ln K

so ln K = - DGo/R.T , it depends on DGo, at a standard state

defined at 1bar (constant pressure)

Note that the composition at equilibrium (Kx) can

depend on pressure but not the above defined K —Preceding ::unsigned comment added by ::201.11.138.212 ([[User ::talk:201.11.138.212|talk]]) 21:14, 29 May 2008 (UTC)

Please see Equilibrium_constant#Pressure_dependence. Best regards, Stan J. Klimas (talk) 23:27, 29 May 2008 (UTC)

[edit] Arrhenius

Main page should probably mention or refer to Arrhenius.

[edit] Empirical Importance

It should be mentioned that van't Hoff equation was very important in the non calorimetric determination of DHo and DSo from plots of ln K x (1/T) adjusting a curve (most times approximated as a line when DHo ~ constant) to empirical data of K at different temperatures. Edgardo. —Preceding unsigned comment added by 201.11.138.212 (talk) 21:20, 29 May 2008 (UTC)