Group 17: Chlorine – Hydrogen Chloride
* Hydrogen chloride is prepared in the laboratory by treating sodium chloride with concentrated sulphuric acid.
420K
NaCl + H2SO4 → NaHSO4 + HCl
(sodium chloride) (Cone.Sulphuric acid) (Sodium bisulphate) (hydrogen chloride)
* Hydrogen chloride is a colourless gas with a pungent odour.
* An aqueous solution of hydrogen chloride is also called hydrochloric acid.
* Because of its ability to dissociate almost 100% to produce hydronium ions (H3O+), hydrochloric acid is considered a strong acid.
HCl(g) + H2O(1) + → H3O + (aq) Hydrochloric acid + Cl– (aq) Ka = [H3O+]Cl/HCL =107
(Hydrogen chloride) (water)
Hydrochloric acid:
* Reacts with ammonia t form dense white fumes of ammonium chloride.
NH3 + HCl → Nh4Cl
Ammonia Hydrochloric acid Ammonium Chloride
* Decomposes salts of weaker acids.
Na2CO3 + 2HCl → 2NaCl + C02 ↑ + H20
Sodium carbonate Hydrochloric acid sodium chloride carbon dioxide Water
NaHCO3 + HCl → NaCl + C02 ↑ + H20
Sodium bicarbonate Hydrochloric acid sodium chloride carbon dioxide Water
Na2SO3 + 2HCl → 2NaCl + S02 ↑ + H20
Sodiumsulphite Hydrochloric acid sodium chloride sulphur dioxide Water
Hydrochloric acid:
* Is used in the manufacture of chlorine, and chlorine, and chlorides like ammonium chloride.
NaOCl + 2 HCl → Cl2 + H2O + NaCl
Sodium hypochlorite Hydrochloric acid Chlorine Water sodium chloride