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Nitrox2
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Yes it's a coffee filter, I'm a little lost as to why it wouldn't work? I thought it had small enough pores.
Anyone else want to corroborate?
Also, when filtering a precipitate, from say a test tube, can one just let the precipitate settle and then decant the fluid?
[Edited on 7-7-25 by Nitrox2]
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bnull
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| Quote: | | Yes it's a coffee filter, I'm a little lost as to why it wouldn't work? I thought it had small enough pores. |
It doesn't. Fresh copper oxalate is a pest to filter: did you notice that the filtered solution is practically the same color as the unfiltered one? I
don't know if it has to do with the solubility of copper oxalate or how fast the crystals are formed, most probably both, but the crystals are very,
very small.
| Quote: | | Also, when filtering a precipitate, from say a test tube, can one just let the precipitate settle and then decant the fluid? |
Usually yes. Some precipitates take a long time to settle, especially when concentrated solutions are used. Others need to age in order to increase
the size of the crystals, which is the case of copper oxalate. In both situations, letting the solution rest for a while is less taxing on your
patience than filtering right away and seeing the filtration fail again and again. Of course, some substances degrade with time (oxidation by
dissolved oxygen, photodecomposition) and you need to remove them from solution as fast as possible, as is the case with copper (i) chloride.
[Edited on 7-7-2025 by bnull]
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Nitrox2
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Doing a fresh batch, I need to brush up on my stoichiometry, but Gemini quickly stated .721g of oxalic acid to 2g Copper sulfate Penta hydrate.
I dissolved as much of the copper sulfate Pentahydrate as I could this time, I wasn't able to get it all to dissolve in the smaller capacity of my
test tube, so I filtered the undissolved copper sulphate Pentahydrate.
I then added .72g of oxalic acid to the test tube, and mixed the two.
Here are before and after photos, I've got it in the freezer right now. I'm wondering if it will aid in the precipitation.
How would one retrieve the product from a cotton ball? I've never had to think of using qualitative paper or anything more than a coffee filter, as
far as I know.
Is this the same, or better or worse, as is a cotton ball plugged in the funnel stem?
What other copper salts degrade in the air and or light and what do they turn into?
 
I decanted the fluid a bit, I will give it a few days to see if it clears up.
Additionally, I thought precipitations happen rather quickly so longer as there is good mixing --
I'm not sure either why it's retaining the color
And, it is, passing right through the coffee filter paper!
When you say plug the stem with a cotton ball, is this in addition to a filter?
Ps I used bars keepers friend as my oxalic acid source
[Edited on 7-7-25 by Nitrox2]
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bnull
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| Quote: | | Doing a fresh batch, I need to brush up on my stoichiometry, but Gemini quickly stated .721g of oxalic acid to 2g Copper sulfate Penta hydrate. [...]
Ps I used bars keepers friend as my oxalic acid source |
Oxalic acid is usually sold as the dihydrate (~126 g/mol). This would mean about 1 g of acid to 2 g of copper sulfate. Bar Keepers has other stuff in
it, such as a surfactant (most probably the sodium salt of an alkylbenzene sulfonate) and an abrasive (quartz, feldspar). If you're in the UK, there
will be no more than 10% oxalic acid (unless it comes from a pre-regulation batch). Assuming that your Bar Keepers is 10% oxalic acid, you would need
ten times the figure I gave, that is, 10 g of Bar Keepers to 2 grams of copper sulfate pentahydrate.
| Quote: | | How would one retrieve the product from a cotton ball? I've never had to think of using qualitative paper or anything more than a coffee filter, as
far as I know. |
The funnel with a cotton ball is basically a poor man's Büchner funnel. Take a piece of cotton, push it into the funnel and hold it with your thumb
or middle finger while you compress it from the stem with a glass rod, pen or pencil. the top of the cotton need to be a little bit above the joint
between stem and cone of the funnel. To retrieve the product, invert the funnel over a filter paper and push the cotton ball with a glass rod, then
scrape the product from the cotton the same way you would do if you had used a filter paper. No secrets here. And no, you don't need to use a filter
paper in addition to the cotton ball.
| Quote: | | What other copper salts degrade in the air and or light and what do they turn into? |
Copper (i) salts in general oxidize in the air. Chloride, iodide, I think the bromide does it too. I don't remember any photosensitive copper salt.
Silver, on the other hand...
| Quote: | | Additionally, I thought precipitations happen rather quickly so longer as there is good mixing |
Yes, precipitations can be really fast, but the same can't be said of the settling of the precipitate at the bottom of the flask. It has to do with
particle size and shape, adsorbed water and whatnot.
| Quote: | | I'm not sure either why it's retaining the color |
Not enough oxalic acid. Add more. Since we're at it, use solutions of the substances when you want to make a precipitate. You don't want to cake it
with the powder.
| Quote: | | And, it is, passing right through the coffee filter paper! |
Like I said, the pores are too large. If you don't want to use cotton, try newspaper (the cheapest is the best) or a laboratory filter paper. Don't
need to go fancy, AliExpress grade is fine for that.
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Cathoderay
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I'm seeing the sciencemadness server slowing down.
I'm not sold on the coffee filters being too coarse, but maybe.
A way of separating very find precipitants is using a centrifuge. Something you might have seen if you watched some of the videos I recommended. But
then something like a centrifuge may be out of your price range.
I think your main problem was not discussing what you wanted to do beforehand. You act like you are working on state secrets.
If you had said that you were going to use "Barkeeper's Friend" as your oxalic acid someone may have steered you straight. I hate to be the one to
burst your bubble but most over the counter things are mixtures with other chemicals included. The label often lists the active ingredients and/or
dangerous ones. However they are not necessarily the major portion. "Barkeeper's" might be mostly silica powder for instance. You could find out how
much oxalic acid is in it by titrating with a standardized base solution and a pH indicator. The silica powder may be clogging the filter for another
thing. The oxalic acid solution should be clear. Filtering it beforehand would have been a good idea. The surfactant (detergent) might also be
effecting the results.
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bnull
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| Quote: | | I'm not sold on the coffee filters being too coarse, but maybe. |
See this thread and NurdRage's video on sulfuric acid from sulfates.
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Cathoderay
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I didn't know what Nitrox2 was after, seems like it is sulfuric acid.
Yes, I was going to suggest NurdRage's video about it. I believe that NurdRage addressed the ferric/ferrous (oxidation state) in his video.
I did think about diatomaceous earth also. Often you can find that at a gardening store.
I'm not sure Keras' conclusion was accurate, he should have distilled the liquid before he titrated it. There could be more oxalic acid remaining than
his estimate. Results have to be proved without a doubt.
However, I doubt Nitrox2 should be distilling sulfuric acid at this point and with the equipment he has. That is a process that is very hazardous.
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bnull
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| Quote: | | I didn't know what Nitrox2 was after, seems like it is sulfuric acid. |
No, it is copper oxalate itself.
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Cathoderay
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Oh, sorry, I missed that.
In that case the diatomaceous earth would not be a good choice. It would be hard to separate the DE from the copper oxalate.
Filter paper does come in different grades, but even the finest might not be enough.
then there are membrane filters but those probably are expensive.
https://www.fishersci.com/us/en/catalog/search/products?keyw...
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Nitrox2
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Think this pretty much completes it for now.
This should be all
Maybe a nicer funnel and get a bend in my straw for usage as a gas delivery tube.
Thanks everyone for the advice!
[Edited on 7-9-25 by Nitrox2]
[Edited on 7-9-25 by Nitrox2]
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Cathoderay
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OK.
I would add more breakers of various sizes, easier to clean than the conical flasks.
I couldn't help but think about your effort to make copper oxalate. You might try various ways of producing crystals of a larger size to help
filtering work.
Some things you could try: more dilute solutions (slowing down the reaction because the active molecules would be farther apart), running the reaction
at colder temperature.
If you stick with "Barkeeper's Friend" I would filter out the silicate first and re-crystallize the oxalic acid to purify it. The surfactant would
still be in it in small amount.
Since you are not after sulfuric acid how about reacting the copper sulfate with sodium oxalate instead. Instead of having sulfuric acid in the
solution afterwards you would have sodium sulfate. Making it that way might make bigger crystals.
You could convert oxalic acid to sodium oxalate by reacting it with sodium hydroxide.
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Nitrox2
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I added some aluminum can tabs to a string to try to make copper sulphate crystals on a string from copper sulphate solution.
I noticed bubbling, I asked GEMINI why, but forgot the reasoning.
It did say that copper is being plated onto the aluminum tab because it (Aluminum) is more reactive of a metal than copper, based on the reactivity
series or activity series. This seems new to me, I've taken up to general chemistry 1, but do not remember these terms. I thought it perhaps had to do
with the electronegativity.
My first plating!
[Edited on 7-10-25 by Nitrox2]
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Cathoderay
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It may be more like a deposit of copper, if a powder rubs off easily it and does not leave a copper coating behind then it is a deposit. Aluminum is
tricky to plate because the metal wants to bond with any oxygen around and the aluminum oxide is very tough and inert.
Here again there may be an issue of purity. Most aluminum you come across will be an alloy of aluminum and other things like magnesium, copper, zinc,
silicon or iron. Most alloys are at least 90% aluminum however.
The bubbles could be oxygen released from the surface oxide or some reactions with the alloying additives.
I think Wikipedia is better source of info that Gemini.
https://en.wikipedia.org/wiki/Aluminium_alloy
It turns out that the alloy used on the top of aluminum cans is a different alloy than the rest of it. I think the top is 3004 or something.
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Nitrox2
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If anyone is curious about my wooden stand, the rod wobbles.
I think it's the weight at the top and the flexibility of the wood.
[Edited on 7-11-25 by Nitrox2]
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bnull
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It is hydrogen. Copper sulfate has a little sulfuric acid remaining from the manufacture process.
Edit: But you also have copper in contact with aluminum in a solution with copper ions, so it has probably more to do with local
electrolysis than a simple reaction with acid. Maybe both.
If you want copper sulfate crystals, make a saturated solution in a beaker, cover it with a PVC film, wax paper or even aluminum paper and poke holes
in the covering. You get a slower rate of evaporation and the crystals have more time to grow.
If you want metallic copper crystals (that's what the aluminum tabs suggest), add copper sulfate to a test tube, fill it with dry sodium
sulfate, cover it with a disc of filter paper and put a small disc of steel (cut it from a metal can, mind the fingers) on top of the filter paper.
Add a saturated solution of the alkaline sulfate until it is about 0.5 cm above the steel disc. Cork the test tube and leave it alone for a few weeks.
The result are small metallic copper crystals, something that you can't make if you use copper sulfate solution. Sodium sulfate lenghthens the time
that copper ions take to diffuse to the top so you get crystals rather than a crumbly sponge.
Take a look at the book From Crystal to Solution by Krestov and Kobenin (https://mirtitles.org/2012/07/04/from-crystal-to-solution-kr...).
[Edited on 11-7-2025 by bnull]
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Nitrox2
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I heard the solution becomes acidic from dissolving copper sulphate, or something like that. Will double check everything
[Edited on 7-12-25 by Nitrox2]
 
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Nitrox2
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Picked up about a foot of latex and some sodium hydroxide today.
I'm wondering what type of file I need to score the glass to get a clean break.
Also I'm wondering why there is what appears to be a mutagenic label on the NaOH?
[Edited on 7-15-25 by Nitrox2]
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bnull
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| Quote: | | I'm wondering what type of file I need to score the glass to get a clean break. |
It's got more to do with making a single score and a quick snap. If there are multiple scratches, chances are the cut will be uneven.You can use a
triangular file, a glass cutter (carbide wheel or diamond tip), a piece of tungsten carbide or even a quartz shard. I've used the file, the carbide
glass cutter and quartz.
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Cathoderay
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As bnull and I suggested a month ago, reading some books may answer many of your questions.
A link to the library.
https://library.sciencemadness.org/library/index.html
Look almost half way down the page, a book titled "Golden Book of Chemistry Experiments" by Robert Brent. That book was published in 1960 for
teenagers.
There are some simple experiments and ways of making equipment. It seems like there were easier ways of getting some chemicals then, some are no
longer available over the counter these days. It shows a way to cut glass tubing with a triangular file. I think your glass tubing is borosilicate so
you would need a very hot flame to soften it.
In general if you don't take good advice people will stop offering it.
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Nitrox2
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Sorry, I was not clear in my last post. I was looking for a common at home item I could use to make a clean cut, Gemini mentioned a nail to score the
glass, heating the glass, and then submerging it, in water.
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Texium
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Quote: Originally posted by Nitrox2  | Sorry, I was not clear in my last post. I was looking for a common at home item I could use to make a clean cut, Gemini mentioned a nail to score the
glass, heating the glass, and then submerging it, in water.
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That’s shit advice. Don’t trust Gemini or other LLMs. Ever. In fact, please don’t post the crap you
get from them here. If you don’t want advice from real people, leave.
Anyway, just buy one of these like bnull suggested: https://www.amazon.com/XAQISHIRE-Triangular-Without-Suitable...
It’s cheap and does the job perfectly. It’s useful to have on hand.
Also, don’t think you’re fooling anyone. It’s painfully obvious that you are an Yttrium2 sockpuppet. I won’t ban you yet but you’re on thin
ice.
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Cathoderay
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Almost any hardware store has triangular files.
You should get out more and explore places like hardware stores, gardening stores, pharmacies, etc. Just keep your eyes open and remember what you
see.
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Nitrox2
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| Quote: Originally posted by j_sum1 | | Quote: Originally posted by Nitrox2 | Would I need to add a Claisen adapter to this to prevent contamination from bumping?
[Edited on 15-6-2025 by Nitrox2] |
That's a short path designed to run under vacuum and collect several fractions without breaking the vacuum.
That's not a beginner setup. And does not need a claisen.
OTOH a short path condenser is very convenient even if it is not used as designed. For versatility however, nothing beats a 300mm liebig.
If you are distilling anything, add to your list an aquarium pump and some tubing. |
Why would the Lisa Nichols demonstration need a claisen adapter to prevent bumping from contaminating the recieving flask and not the micro short path
apparatus, which uses the same, if not similar, micro short path condeser?
Wouldn't it be needing a claisen adapter too? Why or why not?
[Edited on 7-17-25 by Nitrox2]
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Sulaiman
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currently available via online shopping sites at less than usd20 with p&p
h
CAUTION : Hobby Chemist, not Professional or even Amateur
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