Ive leaned from these experiments to expect failure later on.  In this setup, there is no real positive pressure as I am using the spout of the cylinder for the entrance of the wires. Its only a small gap but its still a gap and although the hydrogen is flowing out, some air could be coming in. 

The mercury is quite deep in the cylinder and I would expect the bubbling hydrogen to purge a lot of the oxygen out but who knows.  The upper Pd/Pt is succeptible to air and its strange behaviour in low hydrogen flow may be due to a little air entering the cylinder on top.

Lets see what the Platinum down there does.   There is very little hydrogen dissolved in water but perhaps enough to for a couple with water on the Pt.  Mercury dislikes hydrogen, so the activity of hydrogen is lower on its surface. 

The reduction  potential on the Pt shoud be around -0.83V  for H2/H2O/OH- in 1M NaOH. This will be quite accurate in the cell.

that for Hg/Hg2+   is +0.85 but in standard conditions, so here it will not be that, but will be a mixed potential which will include the sum of the above hydrogen couple. how much influence any of these have on the actual potential will depend on their kinetics ie: current densities.

Any oxygen will raise its potential substantually.

If there is a positive outcome in a few days, when I got back to the lab, a sealed version will be made.

So in my books, it looks positive, although it has no power, but I will need to completely seal it to be sure.

 

Please note mr pomodoro, I've already declared your mercury/palladium experiment a success.I want to see if you can follow up on this now.

Ok  pomodoro you can handle it (-:. Work with me please.don't tinker.leave the tinkering until you are finished with live experiments.viewers get confused.our main focus was and now definitely is very specificly that palladium sponge vs mercury potential.anything else is distraction.

Continuous flow please pomodoro.Make sure that the end exhaust pipe is under water for pressure and to act as oneway valve.I don't trust any static systems because they cannot purge airleaks. the ideal exhaust rate is about one bubble every 2 seconds.

Ok folks,  this is my latest attempt at a profitis cell.    We have the setup that you can see in the vid below.  Triple distilled mercury is at the bottom of the cylinder. Above it is a magnetic stirrer which I might use later.  In the mercury is a a copper wire, prepared as  seen in the picture. Melted glue prevents any water from seeping up the wire strands.

Up on top is the palladized platimum electrode.

UHP hydrogen is bubbled through the liquid , and pressurises the space between the bung and the electrolyte, which is 1M NaOH (AR) in MilliQ water.  The hydrogen comes out of the cylinder and bubbles through a water 'valve'.

The flow of hydrogen is higher than normal as I have just set the cell up and want to remove oxygen quickly. Its flow will be lowered later.

Voltmeter shows volts of mercury wrt Pd/Pt.   Later cell needs to be shorted to make sure all reducible species are reduced by the hydrogen.

Success will achieved if tomorrow and even later, a healthy voltage still exists between the two metals. 

Video is under this line.
   

i could not move it up as it is compressed in its hole .

Anyway, have a look at the two vids, the first shows the equilibrium current  after approx 18 hours of discharging. You also get to see the result of unshorting the terminals.

The second video shows the potential reached after 5 hours of letting it 'recharge'.

Pomodoro pomodoro tsk tsk.remember when you said your going to with-hold any good info from publication? Naughty naughty (-: