[Pranav]

Problem:
In two vessels each containing 500mL of water, 0.5 mmol of aniline (K_b=10^-9) and 25 mmol of HCl are added separately. Two hydrogen electrodes are constructed using these solutions. Calculate the emf of cell made by connecting them appropriately.

(mmol = milli moles)

Attempt:
This is basically a concentration cell. Since the electrodes are connected properly, I need not worry about which is the anode and the cathode, I have to find the absolute value of emf.

Concentration of H⁺ in vessel containing HCl, a=0.05 M
I have K_b for aniline so I can find the concentration of H⁺ i.e b. It comes out to be 10^-8.

From the nernst equation,
E_cell=E^o_cell-0.059/n * log(b/a)
Here, E^o_cell=0 and n=2, hence E_cell=-0.059/2 * log(10^-8/0.05).

Solving, I get E_cell=0.197 V which is just half of the given answer.

Any help is appreciated. Thanks!

PS: Can someone tell me how do you write latex here?

[Pranav]

Anyone?

[billnotgatez]

@Pranav

The forum rules suggest when you try to get additional attention to your question you try to add some more information - please read forum rules

Additionally, there is a chance that someone who is proficient in your question has not been on the system that day. Or, no one is able to help

To your question about LaTex

There used to be a sticky that discussed LaTex on this board
Comments for Staff and Comments from Staff
http://www.chemicalforums.com/index.php?board=16.0
And I am looking into why it is gone.
My memory is weak but I think our software had support problems with it at one time, but I thought that it was resolved.
I remember consulting a web site that gave Latex help and it worked then.
I will troll my memory some more and let you know.
In the mean time look at the link above because it has stickies about other formatting tools that may work.
Sorry
Bill

EDIT
I located a recent discussion about LaTex on our forum
http://www.chemicalforums.com/index.php?topic=68252.0

[AB]

The individual cell reactions require 2 moles of H+ (after conserving electrons) hence, the expression you're getting should be multiplied by 2 (since power in log comes in the product) and then, you'll get your answer.

[XeLa.]

All looks okay, except for one thing. Why did you let n = 2 for the Nernst equation? Do you know what the n means?

XeLa