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Author: Subject: Chemical Christmas decorations
Bedlasky
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[*] posted on 24-12-2019 at 14:13
Chemical Christmas decorations


Hi.

I wish you happy Christmas and I have for you small Christmas experiment :). It's very easy make this, but sometimes it takes little patience. I don't know exact amount of chemicals, but this isn't important.

I made four colorchanging chemical Christmas decorations today from my stock solutions of K2CrO4, CoCl2 and CuSO4.

1. Make cca 30ml of 2,5% solution of CuSO4.5H2O, add small amount of H2SO4 (just to prevent hydrolysis) and heat it on hot water bath. Then add solid NaCl in to the solution until it turns green. After that cool it in cold water bath to room temperature. It change colour in to turquoise. If solution have still green colour, add dropwise some water.

2. Make cca 30ml of 2,5% solution of CuSO4.5H2O, add small amount of H2SO4 (just to prevent hydrolysis) and heat it on hot water bath. Then add solid KBr in to the solution until it turns brown. After that cool it in cold water bath to room temperature. It change colour in to green. If solution have still brown colour, add dropwise some water.

3. Make cca 20ml of 1,5% solution of CoCl2.6H2O, add cca 10-15ml of concentrated HCl and heat it. Then add solid NaCl in to the solution until it turns blue. After that cool it in cold water bath to room temperature. It change colour in to red with purple hue. If solution have purple colour, add dropwise some water.

4. Make cca 30ml of 1,5% solution of K2CrO4, add 1-3 drops of 5% NH3 solution and some solid NH4NO3 or (NH4)2SO4. Solution have yellow colour, but it isn't typical chromate yellow. Heat in on hot water bath. Solution change colour in to orange. If not, add dropwise some 5% acetic acid. Upon acidification you must cool solution in to room temperature. Cold solution must have yellow colour, if not, add again dropwise NH3, heat it and check again colour of hot solution. I made my K2CrO4 solution from K2Cr2O7 and KOH, so there was very small excess of KOH, so for me it was little laborious find good balance. NH3/NH4+ works as buffer.

These four solutions change their colour with temperature. Colorchange works for eternity, so you may repeat it when you want. It's beautiful Christmas decoration :).

Thanks to woelen for inspiration to make chromate/dichromate decoration :).

Explanation:

1. [Cu(H2O)6]2+ + 3Cl- <--> [Cu(H2O)Cl3]- + 5H2O

[Cu(H2O)Cl3]- + Cl- <--> [CuCl4]2- + H2O

2. [Cu(H2O)6]2+ + 3Br- <--> [Cu(H2O)Br3]- + 5H2O

[Cu(H2O)Br3]- + Br- <--> [CuBr4]2- + H2O

3. [Co(H2O)6]2+ + 4Cl- <--> [CoCl4]2- + 6H2O

4. 2CrO42- + H2O <--> Cr2O72- + 2OH-

With increasing temperature equilibrium shifts more to the right.

IMG_20191224_190951.jpg - 1.5MB IMG_20191224_191624.jpg - 1.6MB IMG_20191224_222609.jpg - 1.3MB IMG_20191224_222948.jpg - 1.2MB

[Edited on 24-12-2019 by Bedlasky]
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Bedlasky
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[*] posted on 5-1-2021 at 11:48


At the Christmas I remembered my experiment from previous year, so I did some writeup and post it on my website.

https://colourchem.wordpress.com/2021/01/05/chemicke-vanocni...

https://colourchem.wordpress.com/2021/01/05/chemical-christm...




If you are interested in aqueous inorganic chemistry look at https://colourchem.wordpress.com/main-page/

"An old friend once told me something that gave me great comfort. Something he had read. He said that Mozart, Beethoven and Chopin never died. They simply became music." Dr. Robert Ford, Westworld
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artemov
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[*] posted on 5-1-2021 at 21:45


My rainbow salts series.

Purple: it looks more purple in real life, tetraamminecopper(II) sulfate, from basic copper carbonate

Blue: copper(II) sulfate, from basic copper carbonate

Orange: potassium dichromate, from chromium metal

Yellow: under preparation, potassium chromate, from chromium metal

Green: under preparation, nickel(II) chloride, from pure nickel coins

Red: no idea lol

20210106_133712.jpg - 108kB
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Bedlasky
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[*] posted on 5-1-2021 at 22:18


Red: cobalt salts are red in colour. Or nickel bis(dimethylglyoximate).



If you are interested in aqueous inorganic chemistry look at https://colourchem.wordpress.com/main-page/

"An old friend once told me something that gave me great comfort. Something he had read. He said that Mozart, Beethoven and Chopin never died. They simply became music." Dr. Robert Ford, Westworld
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artemov
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[*] posted on 5-1-2021 at 22:25


Quote: Originally posted by Bedlasky  
Red: cobalt salts are red in colour. Or nickel bis(dimethylglyoximate).


I did considered dmg, but I'll have to make it from scratch, and nitrites are impossible to get here.

Another possibility are the red violurates, inspired by the violuric acid thread. But I'll have to make it from malonic acid.

I'll look into cobalt salts ... thanks.
Edit: It seems cobalt nitrate and cobalt acetate are quite red, subject to color accuracy of digital pics ... anyone seen them in real life?





[Edited on 6-1-2021 by artemov]
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DraconicAcid
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[*] posted on 5-1-2021 at 22:26


Mn(III) is a nice cherry-red, but its compounds tend not to be very stable.



Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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Bedlasky
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[*] posted on 5-1-2021 at 22:58


Artemov: I saw chloride and sulfate, both have very nice red colour, but I never saw acetate and nitrate.

Draconic acid: Not all are red. Alum is violet, chlorosalts are green, oxide brown.

I myself prepare some Mn(III) aqua complexes in solution and they are violet.




If you are interested in aqueous inorganic chemistry look at https://colourchem.wordpress.com/main-page/

"An old friend once told me something that gave me great comfort. Something he had read. He said that Mozart, Beethoven and Chopin never died. They simply became music." Dr. Robert Ford, Westworld
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artemov
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[*] posted on 5-1-2021 at 23:04


Quote: Originally posted by Bedlasky  
Artemov: I saw chloride and sulfate, both have very nice red colour, but I never saw acetate and nitrate.


Yay thanks!
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sciece nerd
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[*] posted on 6-1-2021 at 01:31


CoCl2 is more of a reddish purple, and CoSo4 is more red but it's closer to light red in powder form (between pink and red) but larger crystals is darker, more red.
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artemov
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[*] posted on 6-1-2021 at 06:02


Quote: Originally posted by sciece nerd  
CoCl2 is more of a reddish purple, and CoSo4 is more red but it's closer to light red in powder form (between pink and red) but larger crystals is darker, more red.


It's really quite hard to find true bright red salts ...



bright-red-shades.jpg - 4kB
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Diachrynic
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[*] posted on 6-1-2021 at 06:14


Quote: Originally posted by artemov  
It's really quite hard to find true bright red salts ...


What about Reinecke's salt?

Possibly one of the nices reds I have ever had.

IMG_6181.JPG - 3.2MB




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artemov
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[*] posted on 6-1-2021 at 07:03


Quote: Originally posted by Diachrynic  
Quote: Originally posted by artemov  
It's really quite hard to find true bright red salts ...


What about Reinecke's salt?

Possibly one of the nices reds I have ever had.



"It was first reported in 1863.[3] NH4[Cr(NCS)4(NH3)2] is prepared by treatment of molten NH4SCN (melting point around 145–150 °C) with (NH4)2Cr2O7"

Wouldn't heating ammonium dichromate be a bit dangerous?
I will need to get hands on some ammonium thiocyanate though ...

Edit: I just read up on the preparation, seems a bit too dangerous for my "lab" ...

[Edited on 6-1-2021 by artemov]
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[*] posted on 6-1-2021 at 07:17


Another true red is aquopentammineCo(III) chloride, but it doesn't last too long, and quickly turns into the purple chloropentammine. It's a light red, on the left in your scale. Other red compounds are silver chromate (a bit on the brownish side) and HgI.




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Bedlasky
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[*] posted on 6-1-2021 at 07:20


[MoOCl(H2O)4]+ is red, but I never tried to isolate it as a solid.



If you are interested in aqueous inorganic chemistry look at https://colourchem.wordpress.com/main-page/

"An old friend once told me something that gave me great comfort. Something he had read. He said that Mozart, Beethoven and Chopin never died. They simply became music." Dr. Robert Ford, Westworld
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TriiodideFrog
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[*] posted on 6-1-2021 at 23:54


Nilered has a good video

https://www.youtube.com/watch?v=BOkIqxwc5zs
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sciece nerd
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[*] posted on 7-1-2021 at 02:03


I took a look of my CoSO4, and I realized it's very red, with a hint of orange, I think it's close enough to bright red for collecting, I think the photo on Wikipedia displayed it's color quite accurately.


220px-Cobaltsulfat.jpeg - 12kB

[Edited on 7-1-2021 by sciece nerd]
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artemov
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[*] posted on 7-1-2021 at 02:34


Quote: Originally posted by sciece nerd  
I took a look of my CoSO4, and I realized it's very red, with a hint of orange, I think it's close enough to bright red for collecting, I think the photo on Wikipedia displayed it's color quite accurately.
[Edited on 7-1-2021 by sciece nerd]


Thanks ... I just ordered some malonic acid and barium nitrite to try making some violuric acid and dimethylglyoxime. Hopefully their derivatives will be red :D
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[*] posted on 9-2-2021 at 06:57


What procedure are you following for the violuric acid prep?



Green QD's so far

Feel free to correct grammar or incorect knknowledge. We are all learning.
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Bedlasky
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[*] posted on 9-2-2021 at 17:02


Housane: Look at this thread



If you are interested in aqueous inorganic chemistry look at https://colourchem.wordpress.com/main-page/

"An old friend once told me something that gave me great comfort. Something he had read. He said that Mozart, Beethoven and Chopin never died. They simply became music." Dr. Robert Ford, Westworld
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artemov
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[*] posted on 10-2-2021 at 02:13


Quote: Originally posted by Housane  
What procedure are you following for the violuric acid prep?


In my mind:
Malonic acid -> diethyl malonate (Fischer esterification with ethanol) -> barbituric acid (with urea + sodium ethoxide/ethanol) -> violuric acid (with sodium nitrite)

Yield should be low I supposed.
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