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chornedsnorkack
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So, europium(III) carbonate, Eu2(CO3)3, is white.
What is the colour of EuCO3?
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Dan Vizine
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Don't know about the EuCO3.
Well, the new Ta foil arrived. The ad said new, unused.... What I got was crumpled scraps, half of it stained green. More &$#%(& delay.
"All Your Children Are Poor Unfortunate Victims of Lies You Believe, a Plague Upon Your Ignorance that Keeps the Youth from the Truth They
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Pok
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@chornedsnorkack: according to the german Brauer handbook EuCO3 is yellow or "lemon yellow". Here is a photo.
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chornedsnorkack
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It´s wholly likely that EuCO3 might be yellow. Yellow is the colour of various Eu(II) compounds.
It is also likely that reaction of Eu with air might form EuCO3 - inter alia.
If you have a solid which may be a mixture of EuO, Eu(OH)2, EuCO3, Eu2O3, Eu(OH)3,
Eu2(CO3)3, and mixed compounds, in unknown ratio, how do you assert that it is specifically EuCO3? Carry
out analysis and demonstrate that it has the correct stoichiometry, ruling out significant impurities of Eu(III)?
Also, if you compare the oxidation of metallic Ba in air (pretty fast), metallic Sr, metallic Ca and metallic Eu, how reactive is Eu compared to those
other metals?
[Edited on 25-2-2017 by chornedsnorkack]
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nezza
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Thanks for the info on Europium (II) colours. Do you have a source ?.
In any case it explains my observations on the reaction of Europium with water, a reaction I videoed recently.
Initially there is a violent reaction producing hydrogen and a bright yellow material.
I presume this is Europium(II) hydroxide.
After the metal has all dissolved there is still effervescence from the yellow hydroxide and it becomes much paler.
Is this Eu(II) reducing the water to hydrogen as in :-
4 Eu(OH)2 + 2H2O -> 2Eu2(OH)3 +H2
If you're not part of the solution, you're part of the precipitate.
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Dan Vizine
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And the new Ta foil arrived again. Much thicker, 0.1 mm. New, and just as Fleaker had suggested, kind of like copper or brass. I'll be able to fold
this up appropriately.
And another delay, I leave for a week of work in Mexico. Tomorrow.
"All Your Children Are Poor Unfortunate Victims of Lies You Believe, a Plague Upon Your Ignorance that Keeps the Youth from the Truth They
Deserve"...F. Zappa
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Dan Vizine
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I wanted to go ahead and finish off this particular thread.
After forming new tantalum boats in which to treat the europium, I proceeded to do just that. The europium was flattened into approximately 3 mm thick
slabs and loaded into the boats. The boats were then inserted into the quartz tubing, the tubes were fitted into the tube furnace, the flow of argon
was adjusted to 2 ft.³ per minute and heating was started. The samples were brought to 800°C and held there for about 1.5 hours.
The characteristic blue-gray material continued to sublime off the europium, and while still hot the europium surface was a brilliant silver color.
Heating was then discontinued but argon flow remained on. The tube was removed from the furnace carefully and allowed to cool to room temperature. The
end not connected to the argon was opened and the flow was increased to 5 ft.³ per minute.
Preprepared, dried & argon purged sample tubes were ready. The quartz tube was gently inclined to allow the boats to slide toward the open end at
which point tweezers were used to quickly transfer samples into the sample tubes. The tubes were sealed under argon and a typical sample is shown
below.
The overall recovery was not exactly stellar, 61%. The nature of the blue-gray material remains a mystery. It's not europium metal, and it's not
europium nitride (at least according to the way it reacts with water, which is to say not at all).
Europium surprised me in being as sensitive as it is to the atmosphere. It is certainly in the top ten hardest metals to ampoule in a clean state.
Overall, my impression is that if you want clean europium, buy it that way.
"All Your Children Are Poor Unfortunate Victims of Lies You Believe, a Plague Upon Your Ignorance that Keeps the Youth from the Truth They
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Phosphor-ing
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Could the black compound you described in the first few posts be from residual mineral oil?
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Dan Vizine
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The original color? Who knows?
[Edited on 7/13/2017 by Dan Vizine]
"All Your Children Are Poor Unfortunate Victims of Lies You Believe, a Plague Upon Your Ignorance that Keeps the Youth from the Truth They
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tsathoggua1
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If it reacts as stated with graphitic carbon, what about vitreous glassy carbon crucibles? these are known to resist extremely high temperatures and
glassy carbon is a lot less reactive than graphite, carbon black and the like.
These, vitreous carbon crucibles were in fact, IIRC, the vessels used for the zone refining of some of the first ultrapure semiconductor materials.
They aren't cheap though.
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