Sciencemadness Discussion Board

Copper sulfate

binaryclock - 10-4-2013 at 09:54

Hello I'm trying to get my hands on Copper Sulfate to create zinc sulfate. However the only root killer I can find in the stores around me are made up of Copper (II) sulfate pentahydrate. Can I use this to create zinc sulfate using this method?

http://www.instructables.com/id/How-to-make-Zinc-sulfate-and...

If not, where can I find a good source of copper or zinc sulfate? Any ideas of off-the-shelf products that I can look for?

Thanks

[Edited on 10-4-2013 by binaryclock]

MrHomeScientist - 10-4-2013 at 10:08

The pentahydrate is what you want. Pentahydrate simply means there are 5 water molecules for each CuSO4 molecule in the crystal. You're dissolving it in water anyway, so it makes no difference. You do, however, have to take the crystal water into account when doing your stoichiometry.

binaryclock - 10-4-2013 at 10:33

Thank you sir. There's a lot to learn in this great hobby and even more great people willing to help people out.

MrHomeScientist - 10-4-2013 at 10:51

A neat experiment is to powder some hydrated (blue) copper sulfate, put it in a test tube, and heat it strongly. It loses all its water molecules at 200C and transforms into a white powder. After cooling, adding a little water immediately makes it go blue again. On my Youtube channel I dehydrated a large single crystal using conc. sulfuric acid, and eventually it crumbled into powder!

elementcollector1 - 10-4-2013 at 11:16

Quote: Originally posted by MrHomeScientist  
A neat experiment is to powder some hydrated (blue) copper sulfate, put it in a test tube, and heat it strongly. It loses all its water molecules at 200C and transforms into a white powder. After cooling, adding a little water immediately makes it go blue again. On my Youtube channel I dehydrated a large single crystal using conc. sulfuric acid, and eventually it crumbled into powder!

I saw that. :P
I would do the same with mine, but I have yet to grow a large crystal. I'm assuming that dissolving the CuSO4 in the minimum amount of water at 100 C and cooling slowly, such as in Styrofoam insulation, would work?
Still, I might just keep the crystal - copper crystals show up strangely often in the "Pretty Pictures" thread.

MrHomeScientist - 10-4-2013 at 13:18

They are gorgeous crystals definitely, I love their deep blue color. It was a bit of a shame to destroy one, but it was a neat experiment :) The way I made mine was making a saturated room temperature solution and letting it slowly evaporate over a few months. A bunch of tiny crystals form first, so I picked out a few good looking ones and swept out the rest. Whenever new small crystals would form I'd move them out of the way before they ran into my nice big ones. That's something I need to make a video on, it's been requested a few times. Slow cooling of a heated solution in a well-insulated box would be much faster, but somewhat less controllable! :P

cyanureeves - 10-4-2013 at 14:59

you can make lead acetate this way also if you use vinegar instead of water and lead in place of zinc.plante showed me this method which is pretty fast too and both solution turn clear alike also.

annaandherdad - 21-5-2013 at 09:54

Quote: Originally posted by MrHomeScientist  
They are gorgeous crystals definitely, I love their deep blue color. It was a bit of a shame to destroy one, but it was a neat experiment :) The way I made mine was making a saturated room temperature solution and letting it slowly evaporate over a few months. A bunch of tiny crystals form first, so I picked out a few good looking ones and swept out the rest. Whenever new small crystals would form I'd move them out of the way before they ran into my nice big ones. That's something I need to make a video on, it's been requested a few times. Slow cooling of a heated solution in a well-insulated box would be much faster, but somewhat less controllable! :P


This is very interesting. How did you remove the small crystals? With tweezers? Won't the metal react with the CuSO4? Thanks...

MrHomeScientist - 21-5-2013 at 10:14

Nah I just swept them aside with a plastic spoon. There's so many tiny crystals that picking them out one by one would take forever. I kept my bigger crystals in the center of the dish and just scraped the little ones out of the way before they ran into each other. If there is too much extra buildup you could always transfer your good crystals into another container and filter the solution over to that one. If your liquid level gets too low, make another saturated solution with your "waste" crystals and pour that in as well.

Make sure any solution you add is saturated though! In my experiment, my crystals actually shrunk a few times because the extra liquid I added wasn't quite saturated enough.

annaandherdad - 21-5-2013 at 10:51

Thanks, I'll try that. As for always adding a saturated solution, a wild card in the case of copper sulfate is the temperature. Saturated at one temperature is unsaturated (maybe greatly so) at a higher temperature.

I've enjoyed your videos, btw.

Bot0nist - 21-5-2013 at 10:58



My beautiful pentahydrate crystals on a copper pipe. More pics and a brief write up in the "Pretty Pictures" thread.

http://www.sciencemadness.org/talk/viewthread.php?tid=14644&...

I know, I have no shame... ;)

MrHomeScientist - 21-5-2013 at 11:36

Quote: Originally posted by annaandherdad  
Thanks, I'll try that. As for always adding a saturated solution, a wild card in the case of copper sulfate is the temperature. Saturated at one temperature is unsaturated (maybe greatly so) at a higher temperature.

I've enjoyed your videos, btw.


That's true for any chemical's solubility, but yes particularly so for copper sulfate. It's almost 7x more soluble at 100C than at 0C!

Another thing to keep in mind for CuSO4 crystal growing is that when first dissolving your commercial-grade stuff (assuming you got root killer like I did), you'll want to filter off any insolubles. I find that usually some copper carbonate is in these OTC samples.


Pretty crystals Bot0nist! I've seen some people use rocks as substrates, too. Also If anyone hasn't seen this yet, someone made an art installation by filling an apartment with 75,000 liters of CuSO4 solution to coat everything in crystals. Really amazing: http://www.artangel.org.uk/projects/2008/seizure
Not too many pictures of it, unfortunately. Found that in one of the references on the wiki page for CuSO4.

Bot0nist - 21-5-2013 at 11:40

Thank. Those formed on the pipe after it reacted with the H<sub>2</sub>O<sub>2</sub> / H<sub>2</sub>SO<sub>4</sub> mix it was formed in.

[Edited on 21-5-2013 by Bot0nist]

Eddygp - 21-5-2013 at 12:59

To make CuSO4 crystals, I usually cling a seed crystal on a wire and let it hang in a saturated (sometimes super-saturated) solution of CuSO4. I've got enormous crystals like that, around five or six times larger than Bot0nist's. Not trying to brag about myself...

LanthanumK - 21-5-2013 at 13:10

If you want zinc sulfate, there are some moss killers available that contain almost pure zinc sulfate. It may be cheaper and easier than buying copper sulfate, performing the reaction, and purifying the product.

Godspeed429 - 21-5-2013 at 14:46

You can try to make yourself some zinc sulfate using zinc from pennies and battery acid.
I am currently doing this and so far it is going quiet well.

annaandherdad - 21-5-2013 at 17:53

A question about crystalization, for anyone: How do you keep crystals from crawling up the side of your container and down the outside, finally creeping out onto the table the dish is setting on?

binaryclock - 21-5-2013 at 18:35

I ended up purifying copper(ii) sulfate from root killer by recrystalization. Then making a saturated solution of CuSO4 in H2O and then adding Zn to create ZuSO4.

Bot0nist - 21-5-2013 at 19:49

Quote: Originally posted by annaandherdad  
A question about crystalization, for anyone: How do you keep crystals from crawling up the side of your container and down the outside, finally creeping out onto the table the dish is setting on?


That would make a cool picture... Its known as evaporative creep, and it can be annoying. When I recrystallize my copper sulfate I make a saturated, boiling solution and then place that beaker in a pre heated thermos and then set it in the fridge. The slow cooling from >100C to <15C overnight makes nice, large crystals without the need to evaporate down the solution much.

[Edited on 22-5-2013 by Bot0nist]

annaandherdad - 22-5-2013 at 07:11

Thanks, botonist, having a name for it allowed me to search. I found only three links, all of them on sciencemadness, one of them this one, then another, then a third that Chrome says is infected with malware from darkobulatovic.com. That leaves the second one, which says that you can stop the creep with vaseline. It also says dust landing on the surface of the liquid can seed crystals there, which starts the creep. It is indeed annoying, and I've noticed that sometimes I have it and sometimes I don't.

I have noticed that I seem to have this problem more when I used petri dishes for evaporating, instead of the usual (rounded bottom) evaporating dishes. So I was wondering if there was something special about evaporating dishes that prevent this.

Varmint - 7-6-2013 at 03:35

When I was much younger, I had a near-romance attraction to copper sulfate crystals. Untold hours experimenting.

As other mentioned, the room temp saturation with evaporation allows the best control and can lead to some really emormous crystals with suitable care.

My biggest breakthrough was in controlling the evaporation under my terms.

I took a large glass jar with a nice plastic cover (hard to find back in the 1968-70 timeframe, most covers were still made of metal). I drilled two holes sized for 3/32" aquarium style airline, and heated one to bend it to a gentle right angle with a curve so the air would swirl in the jar.

The second line was plumbed to a cotton-filled film canister with two holes, one the inlet, the second was the exhaust. This served to silence the airflow as it was in my bedroom.

The air source was a cheap aquarium air pump, the quietest I could find. It had a factory air filter pad, but this tended to become saturated with airborne dust and would, presumably with the aid of the ever present vibration, eventually start to dump dust into the airstream.

My solution was another film canister filled with cotton, this one had two holes as well, one the inlet, the other plumbed to a fitting I made from a bottle cap glued over the airpump intake port.

This would run for months at a time, perdiodically refreshing the solution with as close to the original saturation as possible and worked well overall except for the inevitable temperature swings.

One day things would be going well, following a temperature drop you could see crystals getting started elsewhere, or worse, growing at some seed point on the main crystal.

Only solution was to dilute the mother solution until the out of place crystal (and part of the main) was dissolved, setting me back days if not weeks.

As the crystals got bigger (largest was over 1lb) I'd have to replentish the mother solution every other day, then daily, and eventually twice a day before I got tired of the level of maintenence.

I wish I had pictures, but those were the days of film cameras, and I hadn't gotten involved in photography until some years after.

DAS

[Edited on 7-6-2013 by Varmint]

Cou - 7-6-2013 at 12:00

I've seen big containers of copper sulfate pentahydrate in home depot and lowes for $13, it's called Zep root killer