Hydrogen disulphide; Hydrogen persulfide; Hydrogen persulphide, Dihydrogen disulfide
|Molar mass||66.15 g·mol−1|
|Density||1.334 g cm−3|
|Melting point||−89.6 °C (−129.3 °F; 183.6 K)|
|Boiling point||70.7 °C (159.3 °F; 343.8 K)|
Except where noted otherwise, data is given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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The structure of hydrogen disulfide is similar to that of hydrogen peroxide, with two central sulfur atoms and two outer hydrogen atoms. However, the skew angle of the molecule is different, as the H-S-S bond in hydrogen disulfide has a near-standard 90° torsion angle of the syn conformer.
Skew angle in the H2S2 molecule is 90.6°, compared with 113.7° in H2O2. Molecular dimensions in these two molecules are: O-O, O-H, S-S and S-H bonds have lengths of 1.490, 0.970, 2.055 and 1.352 ångströms respectively.
Synthesis and reactions
Hydrogen disulfide can be synthesised by dissolving alkali or alkali earth metal polysulfides in water. When the solution is mixed with concentrated hydrochloric acid at −15 °C, a yellow oil consisting a mixture of polysulfanes (H2Sn) will pool below the aqueous layer. Fractional distillation of this oil gives hydrogen disulfide separate from any other polysulfides (mostly trisulfide).
Quantum tunneling and its suppression in Deuterium disulfide
The deuterated form of hydrogen disulfide DSSD, has a similar geometry to HSSH, but its tunneling time is slower, making it a convenient test case for the quantum Zeno effect, in which frequent observation of a quantum system suppresses its normal evolution. Trost and Hornberger have calculated that while an isolated DSSD molecule would spontaneously oscillate between left and right chiral forms with a period of 5.6 milliseconds, the presence of a small amount of inert helium gas should stabilize the chiral states, the collisions of the helium atoms in effect "observing" the molecule's momentary chirality and so suppressing spontaneous evolution to the other chiral state.
Hydrogen disulfide has been described as "having a severe and irritating odour" that is similar to camphor or sulfur chloride, causing "tears and a smarting sensation in the nostrils". If it is present in high concentrations, it can cause dizziness, disorientation and ultimately unconsciousness.
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- P. Lazzeretti and R. Zanasi (1997). "On the calculation of parity-violating energies in hydrogen peroxide and hydrogen disulfide molecules within the random-phase approximation". Chemical Physics Letters 279 (5-6): 349–354. doi:10.1016/S0009-2614(97)01060-9.
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- Hazardous Reagents, Robinson Brothers
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