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Topic: Solubility of hydrogen and cell potential  (Read 2299 times)

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Offline bmu123

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Solubility of hydrogen and cell potential
« on: February 25, 2015, 04:54:34 PM »
(i)Estimate the solubility of hydrogen in water at the given temperature and
pressure.


Would I use Henry's law for this? so p=1atm/101325Pa

So C = kH x p
I know kH = 1282.05 L atm mol-1 from Wikipedia but not sure that's how I'm supposed to do it!
1282.05 x 1 = 1282.05
Think I'm definitely doing this wrong??

(ii)Given that Eo Ag+/Ag is 0.7990 V at 25°C, give the Eo of the cell and
determine the molality required to produce unit activity of H+. Give full working and reasoning in your answer, explaining any assumptions you make.


No idea what I'm doing here! So Eocell = Eanode - Ecathode and I'm given Ecathode as 0.7990 V. Is the standard hydrogen cell always ) 0 V? Then I'm guessing when I work out Ecell I would draw a graph of molarity vs E and work out the molarity?

Offline mjc123

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Re: Solubility of hydrogen and cell potential
« Reply #1 on: February 26, 2015, 04:30:12 AM »
The units of kH look wrong - multiply by P and you get something in L atm2 mol-1. Looks as if it was meant to go on the other side of the equation: p = kH*C. Try using a value of 1/1282.05 mol L-1 atm-1 in your equation.

Offline mjc123

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Re: Solubility of hydrogen and cell potential
« Reply #2 on: February 26, 2015, 06:30:42 AM »
Standard hydrogen cell is 0V at 298K, 1 atm H2 and aH+ = 1
Use the Nernst equation to determine the E° of a cell with 0.001m Ag+ and aH+ = 1
Use your E-m data to work out the molality at which aH+ = 1

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