Question
Write with equation the following properties of H2S.(i) acidic (ii) reducing and (iii) Precipitation.
Answer
(i) H2S is acidic and reacts with metal hydroxides to form corresponding sulfides and water. For example, with sodium hydroxide:
H2S (g) + 2 NaOH (aq) → Na2S (aq) + 2H2O (l)
(ii) H2S is a reducing agent and can reduce metal ions to their elemental forms. For example, with silver nitrate:
H2S (g) + 2AgNO3 (aq) → 2Ag (s) + 2HNO3 (aq) + S (s)
(iii) H2S can form insoluble metal sulfides when reacted with metal ions in aqueous solutions. For example, with lead (II) nitrate:
H2S (g) + Pb(NO3)2 (aq) → PbS (s) + 2HNO3 (aq)