Need some electrical engineering assistance

[JPG]

I think the d cell limit is an 'in de school building' safety issue.

[heathicus]

That was how we decided to interpret the very vague rules. The information packet they sent home only had a template for the display board and the research paper. No guidelines at all regarding the experiment itself. The rules I listed was just given orally. So we decided that only applied to the displays, not the experiments conducted at home.

So we spent pretty much the whole day doing setup. I used my motorcycle battery charger, and an old motorcycle battery that stopped holding a charge.

We used 3-quart water bottles that are a little larger diameter and a little shorter than a 2-liter coke bottle as our tanks (had to cut the tops off).

Soup cans with tops and bottoms cut out and cut from top to bottom and spread out as the anode.

For the cathode, the only thing I could find three of that were equally rusty and would fit in our tank was some lengths of heavy wire. I wish we could have found something better, but it is what it is. I know where I can get some pretty rusted railroad spikes. I might see if I can procure those in the morning or later tonight after supper.

We ran out of enough daylight to take good pictures, so that's why we're continuing tomorrow. But everything is ready to go and has been tested. Even without the battery, we were getting good results from just the charger. Between 0.5A and 1.25A with just the charger. Between 1.0A and 2.25A with the battery added. Not being an electrical engineer (and not having stayed at a Holiday Inn Express last night) is that a sufficient range to see different results?

[heathicus]

Edit: Double post

[JPG]

So delete it! Posts can be deleted, thread starters cannot.

I think the 'wire' will produce very quick results at that current, so early monitoring would be prudent.

Did you read yer PM I sent you?

I was going to suggest the home charger/battery / school d cell, but was not sure if that was 'kosher'.

Do not tell the science 'teacher' about the hydrogen and oxygen!:rolleyes: 'Teach' should already know.

[heathicus]

Got the rusted railroad spikes this morning. So far, success! Taking lots of pictures. Checking the spikes and taking pictures every 30 minutes. I wish I had a more scientific method of determining rust removal other than visual inspection.

[JPG]

Got the rusted railroad spikes this morning. So far, success! Taking lots of pictures. Checking the spikes and taking pictures every 30 minutes. I wish I had a more scientific method of determining rust removal other than visual inspection.

De color should be changing. De high current one should turn black first.

When 'complete' and if none of them are black, cut or drill a hole carefully so you can maybe see a difference in the thickness of the rust.

I don't suppose you weighed(VERY accurately) them first!:D

P.S. Are you observing a difference in bubble or rusty scum production?

[heathicus]

De color should be changing. De high current one should turn black first.

When 'complete' and if none of them are black, cut or drill a hole carefully so you can maybe see a difference in the thickness of the rust.

I don't suppose you weighed(VERY accurately) them first!:D

P.S. Are you observing a difference in bubble or rusty scum production?

I thought about weighing them, but have no way to. We don't even have a bathroom scale. I even asked a few friends and nobody had a postage scale.

We are observing color, bubbles (density and velocity) scum, etc. So far the bubble production is the only noticeable difference.

[biffedit]

Just remember the size of the experiment is not the important part, the results are. You can perform this in mason jars with a lot less requirements for your voltage source and rusty nails instead of re-bar, which may also speed up the process with less metal to run current through.

Also be aware that the process will release Hydrogen and Oxygen which together can be explosive if contained. Smaller experiments will mean less release of gases and a quicker result.

You may also think of using time as a variable instead of varying your current. Start one 3 days before, the next 2 days and the 3rd the day before. Set up your display in reverse order to display the process over time.

Have fun and good luck.

[heathicus]

After 7 hours in the electrolysis, there is visually not much difference between the three test pieces. The piece in the tank with the lowest current has some rust under the head of the spike that the other two no longer have. Otherwise, they all seem to be covered with the same amount of black oxide.

The tanks tell another tale, though. Tank A (with the lowest current) has mildly murky water, some very minute sludge accumulation around the sliver of anode submerged in the solution, and that's about it. Tank C (with the highest current) has much darker water and a good bit of rust flakes and other "crud" floating around and sitting at the bottom of the tank.

One of my coworkers has a small scale that he says will weight in .001 grams. He's going to go get it on his lunch break and let us borrow it. Our plan is to filter the water from each container through some coffee filters, let them dry, then weigh the dried sludge. This should give us a measurable quantity of rust and other material removed from the railroad spikes.

We might should have set up a "control" with a railroad spike submerged in the electrolyte solution with no electricity. But the experiment wasn't to determine the effect of electricity, but the effect of an increase in current. I think we'll be able to measure that.

[heathicus]

Just looked through the pictures on my phone as I was eating lunch. They show differences in the test pieces that we couldn't spot with our unaided eyes.

These are the spikes as they started out. I filed down a spot on the end to clamp the negative wire to and so we could label them.

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And this is our three tanks set up with the anodes adjusted to provide a range of currents. THANK YOU so much JPG40504 for the diagram you made. That opened my eyes more than anything else and provided the basis of our setup.

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What you can't quite see behind tank "B" is the connection block I made for connecting our positive wires to. This allowed us to easily disconnect one of them so we could check and adjust the current as seen here.

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These are the spikes after 3 hours. It's amazing that the camera sometimes sees things in a different way. In the first picture above, they looked a lot more rusted to our eyes than they did to the camera. And we couldn't see those red/orange spots of rust on the "A" spike at the time of the picture below, but the camera could!

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These are the spikes after 7 hours.

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