1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Electronics type wants advice for this.

  1. Sep 6, 2007 #1
    Thought I might ask the pros here.

    I found it difficult to buy tin plated copper and so I took a copper sheet, put it in distilled water with a bar of tin / lead and ran current through it. (anode was in tin / lead bar) The results were amazingly good. Looked like a professional job and I only used a bucket.
    I needed to add a handful of table salt to the bucket to get the water to conduct well.

    My first question is, someone said I might release chlorine gas, but I used distilled water and so I don't think it is true, at least I am not dead yet.

    Second is, It appears to release huge amounts of Hydrogen with the salt in the water making it more conductive. Useful amounts? Any ideas?

    Third question is, what the heck is that white stuff at the bottom of the bucket?
    Last edited: Sep 6, 2007
  2. jcsd
  3. Sep 6, 2007 #2
    What you want is to apply a current to take electrons from the copper anode (letting copper ions dissolve there) and help other copper ions recombine on (and coat) the cathode.

    For electroplating to work quickly, one thing you will need is plenty of copper ions in solution (rather than waiting on diffusion). I imagine one way to achieve this might be to add acid (which initially liberates some hydrogen and dissolves metal).

    Another thing that can happen is electrolysis of water. At the anode you get water molecules also being stripped of charge, increasing hydrogen ions in solution and releasing oxygen gas. At the cathode you get hydrogen gas (in exactly twice the volume of the oxygen). (Although, with the copper anode to dissolve, you might not get the oxygen gas..)

    But since you added salt (NaCl), another thing that can happen at the anode is for all those dissolved chlorine ions to be converted into poisonous gas. (I can't see Na+ leaving the solution, since sodium reacts with water. I know NaOH is white, but I also can't imagine it precipitating out, since that would suggest extremely low pH.. ) Wikipedia advises using bicarb soda instead of salt, to avoid chlorine gas (but says you'll get a blue and green, not white, mix of copper hydroxide and copper carbonate).

    So, what's white? You said you had distilled water, so it can't be impurities... Did you say you put lead (!) and tin into the solution? sa.. this is such a Chemistry question...
  4. Sep 6, 2007 #3
    I called the tin / lead bar the anode because I made it positive electrically. The cathode was the copper foil. I used tin / lead since it is commonly used as solder and was available. I tried tin / silver and it works the same.

    Bubbles occured at an alarming rate at the copper cathode. It was like I had alka-seltzer in the water.

    I did breath the fumes from this and am still alive so there was no chlorine gas. However, the oxygen or hydrogen from the copper plate was huge in volume. I was thinking about trying to burn it directly in a turbine of some sort to see if I could get more electricity out than what I was putting in, just for kicks and giggles.

    However, the white stuff really filled the bottom of the bucket.
  5. Sep 6, 2007 #4
    That was inconclusive, and dumb.
  6. Sep 6, 2007 #5
    Wait, you applied a negative voltage to the copper? That explains the lack of colour. I misread earlier and thought you were trying to coat things in shiny copper, not produce tin plated copper - what is the advantage of that anyway?

    If you have lead in your anode, you can bet the precipitate is lead hydroxide (and probably toxic too). Now, the bubbles at the cathode should indeed be hydrogen, and if all that hydroxide keeps precipitating out then I could believe that chlorine production would slow.

    Hydrogen gas is of course dangerous too (eg. can be highly explosive), but if you do try to extract power from it... well, if you're willing to consider other processes that take some kind of fuel (like petrol, or some refined metal alloy bar) and leave some different kind of waste (not entirely unlike your precipitate), then you can definitely come away with excess electricity (eg. your car alternator produces more than it needs to charge the starter-motor battery).
    Last edited: Sep 6, 2007
  7. Sep 6, 2007 #6
    The advantage of tin plating the copper is that it will not corrode when placed against aluminium. That is why it it tin plated.

    Now the fact that it produces hydrogen in massive amounts, better than using plain water is just a plus. Enough to produce enough electricity to keep the reaction going and some extra would be a real breakthrough for a water powered car. I doubt this since someone surely would have thought of this by now, but then I see this kinda stuff happening all the time. Someone might have never tried to add salt to make the water more conductive before. So I just wonder if it makes enough to burn and sustain the electrical power to make the reaction work. A five gallon bucket took about 15 watts to plate a 3 foot X 1 foot plate in about 10 mins. How much hydrogen, I don't know but there was lots.
  8. Sep 6, 2007 #7
    Why aren't they teaching kids thermodynamics?
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook