Greetings fellow nerds.
Just a quick vlog of stuff i'm doing, not very complicated.
I've been trying to get back into the lab to do things and I'd like to do some electrochemistry.
In particular with copper.
To do this I need large quantities of copper sulfate but for some reason all of my usual domestic suppliers didn't have it and it would take weeks to order it.
I'm going to need a lot more than what i have here.
And I am not paying exorbitant prices for professional lab grade copper sulfate of all things.
So I decided to pull a Thanos and make it myself.
The idea is simple, electrolyze copper metal into dilute sulfuric acid to create copper sulfate and hydrogen gas.
The process is not that hard.
I have some copper metal piping in the back that I'll use as my source of copper and I've already lowered some of it into a fishtank of about 15 liters of water.
I then add one liter of sulfuric acid from drain cleaner.
Ironically my local hardware store had sulfuric acid and copper piping, but no copper sulfate.
Now you'll notice I have a soft drink bottle on the left where I cut out the bottom and I have inserted a copper wire through the top.
This is our cathode compartment and I made it to contain the splatter of popping hydrogen bubbles.
The splatter of popping bubbles makes this process very messy.
Anyway, as you've already noticed I'm applying a current to the system with the copper pipe in the back being the anode and connected to the positive terminal of my power supply,
while the copper wire inside the soft drink bottle is the cathode connected to the negative terminal of my power supply.
5 to 7 amps seems to be about the limit I can go.
If I try to run higher the wires or the terminals become too hot to use.
At the anode, the copper pipe in the back, the copper metal is losing electrons to become copper ions.
At the cathode, most of the electrons are combining with hydrogen ions to form hydrogen gas which bubbles out and escapes.
Needless to say you must do this in a well-ventilated area to prevent hydrogen build up.
Overall, we're swapping hydrogen with copper and converting sulfuric acid into copper sulfate.
Now I said most of the electrons are turning into hydrogen,
but some of the copper ions now filling the solution also get reduced into copper metal and plate out.
This is an energy waste as we're losing copper sulfate in that case.
This is a parasitic side reaction that we want to avoid.
In a complex system we'd have a bipolar membrane barrier to prevent the travel of copper ions.
But in my amateur setup I'm just relying on the fact the copper wire has a small surface area to make the reaction diffusion limited
and to further limit diffusion I'm using the soft drink bottle cathode chamber.
Anyway, i'm not expecting awesome performance, this is a crude and dirty way to make copper sulfate from hardware store materials.
So i'm going to timelapse the process and you can see the copper anode in the back dissolve.
Whenever it's gone I lower more copper into the tank to continue the process.
To save on labor some individuals will use very large copper blocks or ingots which have all the required copper for the experiment.
I admit this copper pipe is not that thick and doing this manually is a bit tedious.
I did not plan this all the way through, but then again, i wasn't planning to make this at all.
Oh by the way, here is a shot of the cathode chamber several hours in, you can already see the parasitic copper depositing side reaction creating copper.
This copper is very weak and spongy and breaks off easily.
Anyway I'm going to keep going until the solution becomes so saturated with copper sulfate that the formation of crystals on the anode blocks further current flow.
This should take a couple of days.
And here we are a few days later.
The power stopped flowing so I turned off the power supply.
About half way through the process the copper deposits on the cathode became so much that I decided to change out the open bottom bottle to this one where I cut a hole the side.
The idea was to contain the copper so less of it would mix in with the copper sulfate.
Despite this being a lot of copper wasted I'll see if I can remelt and reuse it.
It's very spongy so an alternative use might be as a chemical reactant.
Although you may want to wash it first.
Anyway we still produced a lot of copper sulfate crystals that you can see here already crystalizing out.
I'm going to let this evaporate to crystallize more copper sulfate and to speed that up i'm going to blow air over the surface using this computer fan.
And here we are a couple of days later with our copper sulfate.
It's not very pure but I can recrystalize it.
If you want to do that, you would quickly wash off the acid from the copper sulfate, then dissolve the crystals in water.
Filter out insoluble materials.
And then pour it out to evaporate again.
I'm not going to bother since i'll be using this in a refining cell that will get contaminated anyway.
Anyway, that was my quick and crude way of making copper sulfate.
It's not worth it in terms of labor but for some reason I couldn't get actual copper sulfate.
Must be a shortage or something.
Okay so moving on, I also did some lab equipment repairs.
Remember way back my hotplate stirrer suffered a malfunction and it turned out the temperature sensor inside had broken.
Finding a replacement was easy but connecting to the wires was hard since I couldn't use solder.
At the temperatures of a typical hotplate the solder would melt.
So I opted to use copper tape and while this did work it didn't last long.
It recently failed again so this time i'm going to bond the sensors to the wire using electrochemistry.
First we twist the wires and sensor leads to each other for mechanical stability and to get an initial if weak electrical connection.
And there we go.
This is very weak but it's all we need for now.
Now I made two more sensor and wire assemblies so that if they fail in the future, I'll have spares.
Once we have our assemblies, all we do is attach them to the negative side of a power supply and dip them into a solution of copper sulfate and sulfuric acid along with a copper anode.
In series with the electrodes is a 470 ohm resistor to reduce the current.
I then turn on the power to about 1.7 volts and let the copper plate out.
The total current is measured to be around 15 milliamps.
It's hard to see but copper is depositing onto the exposed metal leads.
What's important here is that copper is bonding the metal wires together.
Copper metal has a much higher melting point than solder so it should survive the hotplate temperatures.
Now the perceptive among you might be asking why this copper deposit is strong enough to hold the wires together
but the copper deposit way back in copper sulfate making experiment was spongy and weak.
Well this is because i'm using very low current here so the copper deposits slowly.
If the plating is slow there is more time for the copper atoms to crystalize electrolytically forming strong connections.
In the copper sulfate experiment the current was very high and forced the copper to deposit as soon as possible, resulting in a mess of weak and spongy deposits.
So current control lets you control the strength of the copper deposit.
I left it there for several hours to ensure a good deposit but I didn't want to go too long or else the deposits would get too big and short out.
After the several hours was finished, i washed the sensors in clean water and there we have them.
You can see the previously silver metal leads are covered in copper.
Now for each one I tested the resistance to make sure they were working.
These are supposed to be 1000 ohm sensors.
Two of the sensors worked properly so the processes worked but one of them had excessively low resistance.
Probably the sensor cracked and the electrolyte solution got in to short out the internal elements.
I'm not at all bothered by this.
The sensors are very cheap and i can always make more.
At least now I have two sensors to replace the ones in my hotplate.
And after putting them in the hotplate worked perfectly.
I expect they'll last much longer since they're much better bonded now.
Anyway, so that's my quick update.
I hope to have more videos eventually but I can't really say when.
Hopefully it's not going to be another year.
Thanks for watching.
Special thank you to all of my supporters on patreon for making these science videos possible
with their donations and their direction.
If you are not currently a patron, but like to support the continued production of science videos like this one,
then check out my patreon page here or in the video description.
I really appreciate any and all support.