Sciencemadness Discussion Board - Vanadyl Sulfate crystals

Vanadyl Sulfate crystals

vibbzlab - 24-12-2020 at 08:55

I made some vanadyl sulfate to crystallise. It was really a task. I followed the method as per the brauers textbook of synthetic inorganic chemistry, According to them I should get the crystals in solution ,but instead I got a really viscous blue solution which was concentrated by placing over a waterbath. Then the remaining water was removed by placing in a DIY dessicator with anhydrous cacl2.

The compound then became very thick which was then powdered with pestle
this is the video i recorded on its prep
https://youtu.be/IQDs6neP27Y

[Edited on 24-12-2020 by vibbzlab]

woelen - 24-12-2020 at 10:31

Your material definitely contains vanadyl ions, but I do not think that you have vanadyl sulfate over here. The color is not the deep blue of vanadyl sulfate. One test you could do is add some of the solid to water and see if it gives a clear blue solution, similar in appearance to a clear solution of copper sulfate (a little bit more blue, deeper blue).

I have some VOSO4.3H2O, a commercial product. It looks as follows:

It is quite wet, due to its hygroscopic nature. I obtained it as shown in the picture from the chemical supplier.

vano - 24-12-2020 at 11:00

Quote: Originally posted by woelen

Your material definitely contains vanadyl ions, but I do not think that you have vanadyl sulfate over here.

It may not be pure vanadyl sulfate, but the compound may have this color. I have seen many compounds that are the same, but not exactly the same color. For example when I buy potassium dichromate it is orange, sometimes even red. I can say the same about basic copper carbonate.This is my potassium tetraperoxochromate. Same as other Wikipedias. But if you use concentated peroxide you will get a red powder that has similar properties.

(Of course I do not mean hydrates)

Bedlasky - 25-12-2020 at 00:18

Woelen: It may be VOSO4.xH2SO4.yH2O. I read that such a compound exist. I don't remember exact ratios VOSO4:H2SO4:H2O.

Vano.kavt: Red potassium "dichromate" is probably potassium trichromate or mixture of dichromate/trichromate. It's surely isn't pure dichromate. Look at this.

vano - 25-12-2020 at 00:33

Quote: Originally posted by Bedlasky

Vano.kavt: Red potassium "dichromate" is probably potassium trichromate or mixture of dichromate/trichromate. It's surely isn't pure dichromate. Look at this.

I bought it a few months ago potassium dichromate and it had a reddish color while I separated these crystals from the powder and stored them separately. You think there is no pure dichromate? I have no idea why an unopened product might have been contaminated.

valeg96 - 25-12-2020 at 00:43

Colour of many salts depends on crystal/particle size, pH and T at which it was crystallized, and other factors. Dichromate can have varying shades of orange (the bigger, the darker) but I think, as woelen said, that vibbz's product is most likely not vanadyl sulphate.

Bedlasky - 25-12-2020 at 00:45

This is orange crystals, not red. At least to me

. It look like potassium dichromate. Trichromate is really deep red. Powder have different colour than crystal. Sorry, I imagined, that your dichromate is deep red (as CrO3 or something like that).

https://www.amertek.co.uk/wp-content/uploads/2016/05/potassi...

This is how my K2Cr2O7 looks like.

https://upload.wikimedia.org/wikipedia/commons/6/62/Potassiu...

These crystals are bigger, so they look more redish orange.

https://en.crystalls.info/Potassium_dichromate#Gallery

And here are really big crystals, sometimes looks more redish orange, sometimes orange, depending on light.

[Edited on 25-12-2020 by Bedlasky]

vano - 25-12-2020 at 01:27

Quote: Originally posted by Bedlasky

This is orange crystals, not red. At least to me

this is my potassium dichromate. Look at someone selling on Amazon Its color is lighter than my dichromate. I mean that when I have seen the same product from different companies the colors are often at least slightly different, as mentioned above it depends on many factors. As for the sulfate in the glass, it is wet, see how it sticks to the glass, while the top is dry, and this also determines the color. I made nickel polyselenide yesterday. The dry looked black in color, though I dried more and eventually remained dark gray. In short I can not judge whether this sulfate is pure, although I am not surprised that this compound has a similar color.

[Edited on 25-12-2020 by vano.kavt]

vibbzlab - 26-12-2020 at 17:18

This is the solution of vanadyl sulfate that I made. I think this is it . right?

vano - 27-12-2020 at 02:59

Quote: Originally posted by vibbzlab

This is the solution of vanadyl sulfate that I made. I think this is it . right?

I subscribed to your channel. Now I watched the video where you make it. Pentaoxide looks pure, sulfuric acid is normal too. I think it really is vanadyl sulfate. In general pentoxide is often contaminated. It depends on the country. They are manufactured accordingly or bought from another country, for example a technical substance mostly are in bags, while your oxide is in a small jar, and if the stuffing is not specially or locally sorted, it is most likely pure.

vibbzlab - 28-12-2020 at 19:46

thank you. Yeah the pentoxide was labgrade purchased from chemical supplies. Infact everything including acid is labgrade. Maybe as you said contaminants maybe present insitu

Bedlasky - 28-12-2020 at 21:24

Nice video. I have few questions:

1. Did you filter solution through glass or paper?

2. What about leftover sulfuric acid? You did recrystallization from acetone, but you evaporated it in to the dryness, so all sulfuric acid is in your vanadyl sulfate.

Honestly, I admire you. I don't have patience for this synthesis.

vano - 2-2-2021 at 11:27

Can you try VSO4 and V2(SO4)3 ?

Bedlasky - 2-2-2021 at 13:16

Vano: VSO4 is very air sensitive, this must be prepared under inert atmosphere. V2(SO4)3 is less air sensitive, but still it's oxidized in to VOSO4 by oxygen (but I think that should be possible crystallize it without inert atmosphere). It would be easier to make potassium or ammonium V(III) alum, because they are less soluble and form nice octahedral crystals.

vano - 2-2-2021 at 23:55

Quote: Originally posted by Bedlasky

Vano: VSO4 is very air sensitive, this must be prepared under inert atmosphere. V2(SO4)3 is less air sensitive, but still it's oxidized in to VOSO4 by oxygen (but I think that should be possible crystallize it without inert atmosphere). It would be easier to make potassium or ammonium V(III) alum, because they are less soluble and form nice octahedral crystals.

Copied:
Receiving: Reduction of vanadium (V) oxide with zinc dust or reduction of vanadium (III) sulfate with zinc. Vanadium (II) sulfate, upon careful drying of the solution, precipitates in the form of crystalline hydrate - red-violet crystals. Forms crystalline hydrates of the composition VSO 4 • n H 2 O, where n = 6, 7. Vanadium (II) sulfate heptahydrate VSO 4 • 7H 2 O is called vanadium vitriol. In air, vanadium (II) sulfate is easily oxidized by oxygen and vanadium sulfate is produced. It also can react with cadmium sulfate and sodium fluoride and products are metalic cadmium, Na2SO4 and Na3[VF6].

In short it is possible to make, but I do not know how much it will be possible in the home laboratory. So it should be an interesting compound for you, because in the solution may form complexes, etc.

[Edited on 3-2-2021 by vano]

woelen - 3-2-2021 at 00:12

Making VSO4 or one of its hydrates in the home lab will be VERY difficult. You need to exclude air and you need to keep temperatures low. V(2+) is even capable of reducing water (with production of H2). Making a vanadium(III) salt is more realistic. I have experimented with vanadium(II) and vanadium(III) in aqueous solution. Vandaium(II) slowly turns to vanadium(III) in solution, even when air is excluded. Vanadium(III) can be kept around more easily, but is still somewhat air-sensitive. But I think that with a good desiccator and an "inert" atmosphere (here, "inert" can also be something like propane or butane, which are OTC and cheap) you might be able to make some solid V(III) salt.

vano - 3-2-2021 at 01:05

I know it is a bit of a specific reaction. Unfortunately, I do not have vanadium oxide now, otherwise I would definitely try.

Bedlasky - 3-2-2021 at 12:09

Vano: I don't say that it is impossible to make VSO4 by crystallization. I say, that you need inert atmosphere.

vano - 3-2-2021 at 21:05

I know. I wrote this information to show that simple reactions are described. Plus others will read it too.