Features of the interaction of sulfur and water

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.