# Chemical Forums

## Chemistry Forums for Students => Physical Chemistry Forum => Topic started by: Twickel on September 25, 2012, 04:36:37 AM

Title: Physical Chemistry- Using the integrated Vant Hoff Equation with K values.
Post by: Twickel on September 25, 2012, 04:36:37 AM
The equilibrium concentration of oxygen in fresh water exposed to the atmosphere is given for two temperatures. At 15 degrees celcius equilib [O2]= 630μmol/L at 25 degrees celcius equiln [O2]= 517μmol/L

The expression for the equilibrium constant, K, between the oxygen in the gas phase and in solution is given by K=[O2]/PO2/atm. Where pO2 is the partial pressure of atmospheric oxygen.

I need to calculate the enthalpy of dissolution, I figured I need to use the integrated Vant hoff equation.
But how do I figure out the partial pressues of oxygen so I can calculate the equilibrium constants? I know that P= xa x P^*

[Thank you
Title: Re: Physical Chemistry- Using the integrated Vant Hoff Equation with K values.
Post by: Borek on September 25, 2012, 08:16:23 AM
21% of oxygen in the atmosphere.
Title: Re: Physical Chemistry- Using the integrated Vant Hoff Equation with K values.
Post by: Twickel on September 25, 2012, 08:28:23 AM
so Kp at 25 degrees is equal to 298/[0.21/1]?
= 1,419
Title: Re: Physical Chemistry- Using the integrated Vant Hoff Equation with K values.
Post by: Twickel on September 27, 2012, 03:11:25 AM
Sorry about that, got mixed up.

Is the Kp value at 25 degrees Kp=[517/0.21/1] = 2461?