Page 231 - Chemistry ICSE Class X
P. 231
Study of Compounds – Hydrogen Chloride 217
(or liquor ammonia) is held near them. White fumes are the small
particles of ammonium chloride formed in the reaction.
NH OH(aq) + HCl(g) o NH Cl(s) + H O(l)
4
4
2
ammonium hydrogen chloride dense white fumes
hydroxide or vapour of (ammonium chloride)
hydrochloric acid
With silver nitrate. Both HCl(g) and HCl(aq) give white curdy
precipitate with silver nitrate solution.
AgNO (aq) + HCl(aq) o AgCl(s) + HNO (aq)
3
3
silver nitrate hydrochloric silver chloride
acid (or hydrogen (white curdy
chloride) precipitate)
The precipitate of silver chloride [AgCl(s)] is insoluble in nitric acid,
but dissolve in ammonium hydroxide (NH OH) due to the formation
4
of diamminesilver(I) chloride.
AgCl(s) + 2NH OH(aq) o [Ag(NH ) ]Cl(aq) + 2H O(l)
4
2
3 2
silver chloride soluble diammine
(insoluble) silver(I) chloride
Tests for Chloride Ion (or Chlorides)
–
Following tests may be conducted for testing/identifying chloride (Cl ) ion
salt:
With conc. sulphuric acid. When a chloride salt is treated with conc.
sulphuric acid (H SO conc.), white fumes of hydrogen chloride gas are
2
4
evolved.
When a glass rod dipped in ammonium hydroxide is placed in the
fumes of HCl, white dense fumes of ammonium chloride are formed.
NaCl(s) + H SO o NaHSO (aq) + HCl(g)
4
2
4
sodium chloride conc. sulphuric acid sodium bisulphate hydrogen chloride
HCl(g) + NH OH(aq) o NH Cl(s) + H O(l)
2
4
4
hydrogen chloride ammonium hydroxide dense white fumes
With silver nitrate solution. When silver nitrate solution is added to
the solution of a chloride salt, white curdy precipitate is formed.
–
–
AgNO (aq) + Cl (aq) o AgCl(s) + NO (aq)
3
3
silver nitrate chloride ion white curdy precipitate
(from chloride salt) (soluble in ammonia)
The precipitate get dissolved when concentrated ammonium hydroxide
is added to it.
With conc. sulphuric acid in the presence of manganese dioxide. A
chloride salt when heated with manganese dioxide (MnO ) and conc.
2
sulphuric acid gives chlorine gas. Chlorine gas is greenish-yellow in
colour and bleaches moist litmus paper.
heat
2NaCl(s) + MnO (s) + 2H SO o Na SO 4 + MnSO 4 + 2H O + Cl (g)
2
4
2
2
2
2
sodium chloride manganese conc. sodium manganese chlorine
dioxide sulphuric acid sulphate sulphate
Cl (g) + Blue litmus paper o Litmus paper o Litmus paper
2
(moist) turns red gets decolourised
(bleached)
