Sciencemadness Discussion Board
Not logged in [Login ]
Go To Bottom

Printable Version  
Author: Subject: Chromium to Chromium (III) oxide
Peter_leyw
Harmless
*




Posts: 4
Registered: 21-1-2019
Member Is Offline


[*] posted on 21-1-2019 at 05:23
Chromium to Chromium (III) oxide





Hi,


First post in this forum, old timer (i still remember my chemistry basics lessons from 40+ years ago but i have no knowledge on this)

what would be the process to get Cr2O3 from Cr?

I'm looking for pieces (or chunks) of Cr2O3.

I've seen people using (NH4)2Cr2O7 to obtain Cr2O3 (in powder)


Thanks and glad to have found this forum.

[Edited on 21-1-2019 by Peter_leyw]
View user's profile View All Posts By User
oberkarteufel
Harmless
*




Posts: 47
Registered: 11-12-2018
Member Is Offline

Mood: Mayonesium sulfate

[*] posted on 22-1-2019 at 02:26


Cr2O3 starting from metallic Cr?
I think the best route would be reacting it first with HCl to transform chromium into CrCl3, then adding sodium carbonate (or hydroxide) solution to precipitate Cr(OH)3. Then filtration and rinsing with distilled water. The last step is heating chromium (III) hydroxide, et voilà!

This way you will also get Cr2O3 powder however.

[Edited on 22-1-2019 by oberkarteufel]
View user's profile View All Posts By User
Peter_leyw
Harmless
*




Posts: 4
Registered: 21-1-2019
Member Is Offline


[*] posted on 22-1-2019 at 09:09




Thank you!

i appreciate the informations even if the result is still powdered Cr2O3

Is there any way to get solid pieces of Cr2O3? (compressing the powder is not an option)

I saw someone mentioning growing crystals (no details)

Any informations on this process?

[Edited on 22-1-2019 by Peter_leyw]

[Edited on 22-1-2019 by Peter_leyw]
View user's profile View All Posts By User
Ubya
International Hazard
*****




Posts: 1247
Registered: 23-11-2017
Location: Rome-Italy
Member Is Offline

Mood: I'm a maddo scientisto!!!

[*] posted on 22-1-2019 at 13:12


water chemistry will give you just powderer oxide, you can't make an oxide crystal
so you need to press the powder but it's not an option for you, so just work with the powder





---------------------------------------------------------------------
feel free to correct my grammar, or any mistakes i make
---------------------------------------------------------------------
View user's profile View All Posts By User
Peter_leyw
Harmless
*




Posts: 4
Registered: 21-1-2019
Member Is Offline


[*] posted on 22-1-2019 at 15:23




The issue is that the painting and other fine arts ressources book i found (from the 1800's) mention that:

"If you can procure oxide (of chrome) do so in solid form, and not in powder (as pigment) and it cannot be compacted.

Only in solid form (so not wax either) but this form is very hard to find"

Could they have meant crystals?
View user's profile View All Posts By User
j_sum1
Administrator
Thread Pruned
23-1-2019 at 00:48
MrHomeScientist
International Hazard
*****




Posts: 1806
Registered: 24-10-2010
Location: Flerovium
Member Is Offline

Mood: No Mood

[*] posted on 30-1-2019 at 06:29


I've never heard of bulk solid chromium oxide as a chemical reagent. What use would a solid chunk have that the powder couldn't do?

Apparently there's a mineral form of Cr2O3, Eskolaite. That'd be about the closest you'd get.
View user's profile Visit user's homepage View All Posts By User
fusso
International Hazard
*****




Posts: 1922
Registered: 23-6-2017
Location: 4 ∥ universes ahead of you
Member Is Offline


[*] posted on 30-1-2019 at 06:45


Quote: Originally posted by MrHomeScientist  
I've never heard of bulk solid chromium oxide as a chemical reagent. What use would a solid chunk have that the powder couldn't do?
Polishing?



View user's profile View All Posts By User
oberkarteufel
Harmless
*




Posts: 47
Registered: 11-12-2018
Member Is Offline

Mood: Mayonesium sulfate

[*] posted on 30-1-2019 at 08:16


Quote: Originally posted by fusso  
Polishing?


I can't imagine anyone using solid/fused chunk of Cr2O3 for polishing. Actually, it's the powder that is mixed with molten wax/fats to get the "green polishing paste". The same way, Fe2O3 is used to make "red polishing paste".
View user's profile View All Posts By User
Peter_leyw
Harmless
*




Posts: 4
Registered: 21-1-2019
Member Is Offline


[*] posted on 1-2-2019 at 03:49


Quote: Originally posted by MrHomeScientist  
I've never heard of bulk solid chromium oxide as a chemical reagent. What use would a solid chunk have that the powder couldn't do?

Apparently there's a mineral form of Cr2O3, Eskolaite. That'd be about the closest you'd get.



They mention and recommend the solid form (as pigment) on the canvas or specific surfaces for details (this is what the book mention)

Eskolaite is very expensive (and hard to find)

This is probably the source the book mention.

I found the "american elements" site list Chromium (III) oxide as available in powder and "crystals".

The "solid" form could mean that it was melted?



[Edited on 1-2-2019 by Peter_leyw]

[Edited on 1-2-2019 by Peter_leyw]
View user's profile View All Posts By User

  Go To Top