chornedsnorkack
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Tl properties
Tl compounds are toxic. But so are compounds of Pb and Cd.
How dangerous is metal Tl, in applications where Tl oxidation is, like Pb or Cd oxidation, an unwanted side reaction anyway?
How do the mechanical properties of Tl compare to the other poor metals, like Zn, Cd, In, Sn, Pb and Bi?
How are the properties of Tl alloys, in terms of brittleness and corrosion, compared to alloys of the other poor metals?
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clearly_not_atara
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IIRC it has some similarities to silver: it forms insoluble +1 compounds with halides which are light-sensitive. Wikipedia says it discolors when
exposed to air. That suggests it's much more reactive than other poor metals, which is probably why metallic thallium is rarely encountered. The
patina could pose a dust inhalation risk.
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chornedsnorkack
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Quote: Originally posted by clearly_not_atara  | | IIRC it has some similarities to silver: it forms insoluble +1 compounds with halides which are light-sensitive. Wikipedia says it discolors when
exposed to air. That suggests it's much more reactive than other poor metals, |
The standard first oxidation potentials of poor metals are:
Zn Zn2+ + 2 e− ⇌ Zn(s) -0.7618
Cd Cd2+ + 2 e− ⇌ Cd(s) -0.4
Hg Hg22+ + 2 e− ⇌ 2Hg(l) 0.7973
Ga Ga3+ + 3 e− ⇌ Ga(s) -0.549
In In3+ + 3 e− ⇌ In(s) -0.34
Tl Tl+ + e− ⇌ Tl(s) -0.34
Sn Sn2+ + 2 e− ⇌ Sn(s) -0.13
Pb Pb2+ + 2 e− ⇌ Pb(s) -0.126
Bi Bi3+ + 3 e− ⇌ Bi(s) 0.308
But maybe Tl2O is more prone to crumble or hydrate and less protective than ZnO, CdO, Ga2O3 and
In2O3?
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clearly_not_atara
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Most likely because it's univalent. Thallium (I) hydroxide is significantly more soluble in pure water (34% w/w) than the oxides of zinc, cadmium,
gallium, indium, etc, and gives a "strongly alkaline" solution. Tl2O is described as hygroscopic. So there is essentially no passivation in moist air.
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chornedsnorkack
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Considering the simple binaries...
Bi-Tl
https://himikatus.ru/art/phase-diagr1/Bi-Tl.php
Low solid solubility of Tl in Bi, apparently first Tl containing phase is alpha phase at about 40% Tl. Bi(III) is not amphoteric IIRC
Cd-Tl
https://himikatus.ru/art/phase-diagr1/Cd-Tl.php
Simple eutectic, so Tl crystals separate
In-Tl
https://himikatus.ru/art/phase-diagr1/In-Tl.php
Large solid solubility. Was In amphoteric?
Pb-Tl
https://himikatus.ru/art/phase-diagr1/Pb-Tl.php
Huge solid solubility. And Pb is amphoteric
Sn-Tl
https://himikatus.ru/art/phase-diagr1/Sn-Tl.php
Not soluble in Sn - what separates is gamma phase. And Sn is amphoteric
Tl-Zn
https://himikatus.ru/art/phase-diagr1/Tl-Zn.php
Limited solubility even in liquid, insoluble in solid - and Zn is also amphoteric.
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j_sum1
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I understand that Tl+ mimics K+ in the body. So it interferes with ion exchange channels in the cell. There is can oxidise to its 3+ state with the
result that the cell does not fumction.
I thknk it has a similar action on synapses.
I have both Cd and Tl. I will do chemistry with Cd. I am not even going to open my ampoules of Tl.
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