THALLIUM - Tl

Properties of Thallium:

Silver-white metal, plastic, very soft, fusible. On air becomes covered by an oxidic film. In a compact form doesn't react with water, hydrochloric acid, alkalis, hydrate of ammonia. Is oxidized by sulfuric and nitric acids, hydrogen peroxide, and chlorine.


Molar mass g/mol 204.383
Density g/cm3 11.84
Melting point °C 303.6
Boiling point °C 1457

Methods for preparation of Thallium:

Tl2O(solid) = Tl2O(gas) &harr Tl + O2 (over 1300°C).

Tl2O + H2 = 2Tl + H2O (over 500°C).

Tl2O + CO = 2Tl + CO2 (250-325°C).

2Tl2SO4 + 2H2O → Electrolysis → 4Tl↓(on cathode) + O2↑(on anode) + 2H2SO4.

2TlCl + H2 = 2Tl + 2HCl (650-750°C).


Сhemical reactions with Thallium:

2Tl + H2SO4(diluted, cold) = Tl2SO4 + H2↑.

3Tl + 4HNO3(diluted, hot) = 3TlNO3 + NO↑ + 2H2O.

Tl + 6HNO3(conc., hot) = Tl(NO3)3 + 3NO2↑ + 3H2O.

4Tl + 2O2 = Tl2O + Tl2O3 (400°C, burning on air).

4Tl + 2H2O = + O2 = 4TlOH (50-70°C).

2Tl + 3H2O2(conc.) = Tl2O3↓ + 3H2O.

2Tl + Cl2 = 2TlCl (normal temp.).

2Tl + 2HCl(conc.) + 3Cl2 = 2H[TlCl4].

2Tl + S = Tl2S (320°C, in the atm. of hydrogen).

2Tl + 3S = Tl2S3 (200-250°C).
 

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Absolutely pure gold is so soft that it can be moulded with the hands.