Is H2S water-soluble

Hydrogen sulfide

Author: Hans Lohninger

CAS no.7783-06-4
Molecular weight (1)34.08 amu
Melting point-85.7 ° C
boiling point-60.2 ° C
Density [0 ° C]1.54 g / l

Hydrogen sulfide, H.2S, is a colorless, very foul (like rotten egg) smelling, poisonous gas that dissolves moderately well in water (4.65 l H2S in one liter of water at 0 ° C). The corresponding aqueous solution is approx. 0.1 molar and is called hydrogen sulfide water. Since hydrogen sulphide water decomposes in the air and under the influence of light (sulfur separation), hydrogen sulphide water must be stored in dark bottles that are as full as possible.

Hydrogen sulfide water behaves like a weak dibasic acid, the salts of this acid are hydrogen sulfides and sulfides. While the hydrogen sulfides are readily soluble in water, most sulfides (with the exception of the alkali metal sulfides) are very sparingly soluble or almost insoluble in water. The poor solubility of most sulfides is used in analytical chemistry to precipitate metals in groups (cation separation by precipitation with hydrogen sulfide): Depending on the solubility product, some sulfides precipitate in an acidic solution, others only in a basic (ammonical) medium.

Liquid hydrogen sulfide is a good solvent.

If you heat hydrogen sulfide, it breaks down into its elements; at 1 bar and 1000 ° C the equilibrium is roughly in the middle, i.e. half of the hydrogen sulfide has decayed. Hydrogen sulfide burns in the air - depending on the amount of oxygen supplied - either to water and sulfur dioxide, or to water and sulfur:

2 H2S + 3 O2 2 H2O + 2 SO2
2 H2S + O2 2 H2O + 2 S.

Occurrence and extraction
Hydrogen sulfide is found in petroleum and natural gas (some natural gas wells in Canada have 15% H.2S content) and occurs in very large quantities in crude oil desulphurisation. The easiest way to produce hydrogen sulfide in the laboratory is to use Kipp's apparatus from iron sulfide and hydrochloric acid:

FeS + 2 HCl H2S + FeCl2

However, the hydrogen sulfide obtained in this way is contaminated with hydrogen, since the iron sulfide usually also contains some iron. For the development of hydrogen-free H2It is best to use calcium sulfide instead of iron sulfide. Technically, hydrogen sulfide is produced from the elements at 300 ° C and in the presence of catalysts.
H2S is an insidious poison. On the one hand, it is perceived well below the toxic concentration (smell of rotten eggs, the olfactory threshold is 25 ppb, acute symptoms of intoxication show up from 10 ppm), and on the other hand, paralysis of the olfactory cells occurs even at a relatively low concentration (from 200 ppm) so that H2S is then no longer perceived. From a concentration of 1000 ppm (0.1% by volume), rapid death from respiratory paralysis occurs after just a few breaths. Since the poisoning by H2S is reversible, an accident victim should leave the H2S-containing atmosphere and be ventilated with oxygen if possible (the rescuers must wear respiratory masks and rope up).