These are wonderful. Let me add one of my own to the collection. This is a true story from that same era, maybe a couple of years later when I got kicked out of my third grade class for being a troublemaker and had to go to a special ed class called Mrs. Spencer's Workshop.
199. Make your own printed circuit board
You will need: a common kitchen cutting board, a sheet of copper, a roll of electrical tape, a fish tank, and a supply of nitric acid. And whatever electrical components you need to complete your circuit.
All of these supplies are readily available to a third grader, except for the nitric acid which you will have to ask your teacher to source.
First, design your circuit and test it in your mind. Then tape it out - literally - with the electrical tape on one side of the copper sheet and matching tape on the other side.
Pour the nitric acid into the fish tank.
Dip the copper sheet into the nitric acid. Watch it with your teacher as the acid dissolves the copper, except where you have taped out your circuit.
When all that remains are the taped out traces, remove the copper circuit from the acid and rinse it with water.
Peel off the electrical tape and fasten the copper traces onto the cutting board. This is what makes it a circuit board.
Connect the rest of the components and test your circuit.
Go to the science fair, demonstrate the printed circuit, and explain to the visitors how you made it.
Thanks for your story! I am wondering why your teacher would use nitric acid. Wouldn't iron(III) chloride have been much safer in a workshop with children?
As I recall, it was because I had read up in my chemistry book about what would dissolve copper, and it mentioned nitric acid. So that's what I asked for.
Mrs. Spencer's Workshop was a class where you could pick out your own projects. She would get you the materials you needed, let you do your project, and help you if you got stuck.
You could say that she was my lab assistant here rather than my teacher.
The other safety question for me is why didn't either of us use eye protection!
Diluted enough, the nitric could easily be made weaker than your stomach acid but will still eventually dissolve the copper. Its a sort of linear-ish relationship of concentration vs time so you can trade safety for time (as with most industrial processes, LOL)
I would think dilute iron chloride would not taste good, but you could probably chug enough to get sick.
I believe there would be a similar relationship WRT staining skin and clothes, dilute enough HNO3 would not be TOO much more dangerous than letting kids handle a can of Mt Dew unsupervised, but FeCl in any dilution will stain and damage clothes and skin.
If I had to work with maximal concentration solutions of both, I'd agree and definitely prefer the conc FeCl vs fuming nitric.
199. Make your own printed circuit board
You will need: a common kitchen cutting board, a sheet of copper, a roll of electrical tape, a fish tank, and a supply of nitric acid. And whatever electrical components you need to complete your circuit.
All of these supplies are readily available to a third grader, except for the nitric acid which you will have to ask your teacher to source.
First, design your circuit and test it in your mind. Then tape it out - literally - with the electrical tape on one side of the copper sheet and matching tape on the other side.
Pour the nitric acid into the fish tank.
Dip the copper sheet into the nitric acid. Watch it with your teacher as the acid dissolves the copper, except where you have taped out your circuit.
When all that remains are the taped out traces, remove the copper circuit from the acid and rinse it with water.
Peel off the electrical tape and fasten the copper traces onto the cutting board. This is what makes it a circuit board.
Connect the rest of the components and test your circuit.
Go to the science fair, demonstrate the printed circuit, and explain to the visitors how you made it.
Thank you, Mrs. Spencer.