Hydrogen Product By Photovoltaic Electolytic Cell

[freeztar]

Originally Posted by Turtle

Still little to no Oxygen collecting, but the Hydrogen side is bubbling away and the bottle has collected a wonderful amount of ooky goo. I wonder if it still tastes salty?

So what is the "ooky goo"?

[Turtle]

Originally Posted by freeztar

So what is the "ooky goo"?

I'm no chemist, but I'll go with 'metal oxides' for $100 Alex.

[freeztar]

Originally Posted by Turtle

I'm no chemist, but I'll go with 'metal oxides' for $100 Alex.

I'm sorry, but you'll need to phrase that in the form of a question.

[Turtle]

Originally Posted by freeztar

I'm sorry, but you'll need to phrase that in the form of a question.

My bad! Good thing this isn't the Double round. So...'what are metal oxides?' Alex.

Again I'm no chemist, but if that is a correct question then this may solve the mystery of where the Oxygen went? yes/no?

[CraigD]

Very cool hands-on project!

I did some quick calculations based on wikipedia’s handy table of the energy density of common fuels, and came up with the total energy in your collected hydrogen of 800 to 1000 J. With a nominal input power from your solar cell of 7 W, that would be something like 114 to 143 seconds of charge at 100% efficiency.

Seems like your efficiency is either far, far from 100%, or you’re loosing gas. I wonder, how permeable is PET to hydrogen? According to the linked article, PET is sometimes sandwiched with other materials or coated with aluminum to reduce it permeability, particularly to oxygen, and hydrogen is a much smaller and harder to contain than oxygen.

[Turtle]

Originally Posted by CraigD

Very cool hands-on project!

I did some quick calculations based on wikipedia’s handy table of the energy density of common fuels, and came up with the total energy in your collected hydrogen of 800 to 1000 J. With a nominal input power from your solar cell of 7 W, that would be something like 114 to 143 seconds of charge at 100% efficiency.

Seems like your efficiency is either far, far from 100%, or you’re loosing gas. I wonder, how permeable is PET to hydrogen? According to the linked article, PET is sometimes sandwiched with other materials or coated with aluminum to reduce it permeability, particularly to oxygen, and hydrogen is a much smaller and harder to contain than oxygen.

Danke Craig! So the 4 to 5 ozs. of collected Hydrogen gas contain 800 to 1000 J?

On the nominal 7 Watts, I think we need some clarification as I am not completely clear on all myself. The panel is marked as 5 watts and .35 Amps, and no particular voltage is given other than it's for recharging 12 volt batteries. However, they make the panels to produce higher than 12 volts so they keep working even in cloudy conditions, or so I have read.(as noted earlier I have metered a high of 21 volts in full Sun.) Now given the relationship Volts*Amps=Watts I am unclear whether the amperage remains the same when the voltage varies due to variations in Suns intensity. I'll check my meter for the range of amperage it measures; I know it's small but it may be in the range I can put the meter in the circuit and measure how or if the amperage varies withg the Sun intensity as well.

Given your info on PET I do not think the Oxygen is permeating the bottle, but moreover I see no Oxygen bubbles even accumulating in the bottle covering the positive electrode or on the electrode. As I said before, it may be I don't have sufficient amperage to make the Oxygen bubble off the electrode, but in view of my guess about the goo being metal oxides, perhaps that is where the Oxygen is gone, i.e. it is in those oxides?

I'm in Seattle on holiday right now and I disconnected the cell while I'm away. Im' expecting a lot of the goo will have settled out, but in any regard I will take up the project again as soon as I return.

[Turtle]

Today's report from Noon observations:

Cloudy day; measured output from panel with it disconnected at 14 Volts. I found my meter has 3 scales for DC amperage to 1/2 Amp, i.e. 500mA. With the panel reconnected to the cell and the meter set to Amperes, I recorded 6mA between the positive power lead and the anode. Is this low current compared to the panel rating of 350mA a result of low conductivity in the electrolyte?

Amperes, and Coulombs, and Voltage oh my! As to the missing Oxygen, it is leaking not out of the bottle methinks, but out of the insulation on the anode/positive lead. I replaced it enirely today as the corrosion was apparent at the connection end, 7 inches from the cell.

That's all I got. :

[Turtle]

Report for today's Noon observations:

With some partial Sun breaking through the clouds, I disconnected the panel and measured its output at 18 Volts. Reconnected to the electrolytic cell I measured a current of 23.5 mA between the positive lead of the panel and the anode, and a current of 22.5 mA between the cathode and the panel's negative lead. There is now ~ 12 fl. ozs. of Hydrogen gas collected in the bottle.

As the electrolyte evaporates, small salt crystal matts have formed on the surface and they are accumulating thin deposits of copper. Here is a closeup of the best of these films; largest is ~1/2 inch across. (click image for enlarged view)


I saw an episode of How It's Made on television and they followed the process to make bumpers. When it came to the electrolytic chromium plating, they showed it in action but commented that the exact mix of electrolyte, voltage, current, etcetera were trade secrets. A Black Art indeed.

[Turtle]

Some other Stuff:
I used tap water for the electrolyte mix so it started with some chlorine and likely some fluoride, along with all the local trace minerals and human pollutants. I only mentioned I added salt to the water to improve conductivity, without specifying what 'salt'. So going to check the ingredients on the box of Morton Kosher salt that I used, I see it says 'Salt', & 'Yellow Prussiate of Soda (Anit-caking agent)'. So the plot thickens as does the soup.

What is yellow prussiate of soda, and what is it doing in my soup‽ A chemical by any other name would have the same chemical formula. How's about sodium ferrocyanide? Or maybe tetrasodium hexacyanoferrate? Sodium hexacyanoferrate (II)? Hydrocyanic acid? Ferricyanide?
Sodium ferrocyanide - Wikipedia, the free encyclopedia

Boy am I glad I haven't drank that much of the stuff!*

*disclaimer: for the record I did not drank any of the 'stuff'. .

[GAHD]

Try using carbon for your electrodes, it doesn't oxidize. Mechanical pencil refills work perfectly in such applications. Make sure your transmission wire to the electrode as well as connection points are totally shielded.