Features of the interaction of sulfur and water
What compounds form in the result?
Sulfur is a member of the chalcogen group. This name for the elements in the main subgroup of the 6th group of the Periodic Table may be defined as “forming ores”. Besides sulfur, this list includes:
- oxygen (О);
- selenium (Se);
- tellurium (Те);
- polonium (Po).
On the outer orbital chalcogens have 6 electrons (configuration ns2np4), These two unpaired electrons of the p-sublevel give elements bivalency. In sulfur the paired electrons of the s- and p-orbitals are easily excited, and move to the d-levels and increase the valence of the element to IV and even VI.
Sulfur (S) is a typical non-metal with high activity.
It is obtained by smelting inclusions of the element contained in rock in autoclaves (sulfur is contained in rock in a free state).
Reactions with sulfur
Sulfur can enter into reactions with simple and complex compounds, it can be both an oxidizer and a reducer.
Sulfur enters into a reaction with oxygen and with complex substances (halogens, acids) as a reducer.
Sulfur does not dissolve in water in ordinary conditions.
A dissolution reaction between water and sulfur can only take place under high pressure, and if the water is in the form of vapor:
3S + 2H₂O(vapor) = 2H₂S + SO₂
A solution of sulfur (hydrogen sulfide water) is a weak dibasic acid. Its dissociation takes place in stages:
Н₂S ↔ Н⁺ + НS⁻ (hydrosulfide-ion) — reaction is reversible
НS⁻ ↔ Н⁺ + S²⁻ — reaction is reversible
Application of hydrogen sulfide water and its chemical properties
Hydrogen sulfide mineral springs have long been used for medical purposes, to treat rheumatism and a large number of non-infectious skin diseases.
Hydrogen sulfide water has traditional properties of acids and reacts:
- with basic oxides:
Н₂S + СаО = СаS + Н₂O
- with bases:
Н₂S + NаОН ↔ NaHS + Н₂O
Н₂S + ОН⁻ ↔ НS⁻ + Н₂О
Н₂S + 2NаОН ↔ 2NaS + 2Н₂O
- with salts:
СuSO₄ + Н₂S = CuS + H₂SO₄
Cu²⁺ + Н₂S = CuS↓ + 2Н+
- with metals the reaction of water and sulfur is:
Са + Н₂S = СаS + Н₂↑
Click here to see wonderful safe experiments with sulfur compounds.
Properties of salts of hydrosulfuric acid
Hydrosulfites (acid salts) of hydrogen sulfide water dissolve excellently in water. For example, Са(Н₂S) or NaНS.
Normal salts have different dissociation properties – sulfides of alkaline earth metals and (NН₄)₂S ammonium sulfide are soluble. Sulfides of other metals are insoluble. Sulfide of silver, copper, mercury and other heavy metals do not dissolve even in acids (with the exception of nitric acid).
What reactions of sulfur in an aqueous solution are qualitative
Some sulfides acquire a specific color:
- PbS and CuS - black;
- CdS – yellow;
- ZnS and MgS – white;
- Mn – pink.
The reaction of hydrogen sulfide acid with lead salts is a qualitative reaction (to sulfide – the S₂⁻ ion):
Na₂S + Pb(NО₃)₂ → PbS↓ + 2NаNО₃
S₂- + Pb₂О = PbS↓ — a black sediment.
Combustion of sulfuric acid
Sulfuric acid is a heavy transparent oily liquid. It cannot enter into a combustion reaction (as it is already oxidized to the maximum), only the production of smoke above a concentrated solution in fluorine is possible. But the substance can act as an oxidizer in the combustion of other substances.