Page 226 - Chemistry ICSE Class X

8 Study of Compounds –

Hydrogen Chloride

Hydrogen Chloride
CONTENTS
Molecular formula HCl Nature Polar covalent, gaseous
ͻ WƌĞƉĂƌĂƟŽŶ ŽĨ ŚLJĚƌŽŐĞŶ ĐŚůŽƌŝĚĞ Molecular mass 36.5 u Dot structure
ͻ >ĂďŽƌĂƚŽƌLJ ƉƌĞƉĂƌĂƟŽŶ ŽĨ ŚLJĚƌŽŐĞŶ Molar mass 36.5 g mol –1
ĐŚůŽƌŝĚĞ
ͻ džƉĞƌŝŵĞŶƚ ƚŽ ƐŚŽǁ ƚŚĂƚ ŚLJĚƌŽŐĞŶ Hydrogen chloride is a compound of hydrogen and chlorine. The molecular
ĐŚůŽƌŝĚĞ ŝƐ ŚĞĂǀŝĞƌ ƚŚĂŶ Ăŝƌ formula of hydrogen chloride is HCl. Hydrogen chloride (HCl) is a gas
ͻ ,LJĚƌŽĐŚůŽƌŝĐ ĂĐŝĚ ΀, ů;aq)] under normal conditions. The aqueous solution of hydrogen chloride is
ͻ dĞƐƚƐ ĨŽƌ ŚLJĚƌŽŐĞŶ ĐŚůŽƌŝĚĞ ĂŶĚ called hydrochloric acid [HCl (aq)].
ŚLJĚƌŽĐŚůŽƌŝĐ ĂĐŝĚ
ͻ dĞƐƚƐ ĨŽƌ ĐŚůŽƌŝĚĞ ŝŽŶ ;Žƌ ĐŚůŽƌŝĚĞƐͿ Occurrence
Hydrogen chloride (HCl) gas occurs in
ƒ Volcanic emissions ƒ Gastric juice of mammals

Preparation of Hydrogen Chloride

What are the general methods of preparation of hydrogen
chloride

Following general methods can be used for the preparation of hydrogen
chloride:

By synthesis
Hydrogen and chlorine gases react when exposed to diffused sunlight
to form hydrogen chloride. The reaction is smooth in diffused light, but
explosive in bright sunlight
diffused
H (g) + Cl (g) o 2HCl(g)
EŽƌŵĂůůLJ͕ ŚLJĚƌŽŐĞŶ ĂŶĚ ĐŚůŽƌŝŶĞ ĚŽ 2 2 sunlight
ŶŽƚ ƌĞĂĐƚ ŝŶ ĚĂƌŬ͘ ,ŽǁĞǀĞƌ͕ ŝŶ ƚŚĞ hydrogen chlorine hydrogen chloride
ƉƌĞƐĞŶĐĞ ŽĨ ĐĂƚĂůLJƐƚ͕ ƐƵĐŚ ĂƐ ĂĐƟǀĂƚĞĚ
ĐŚĂƌĐŽĂů͕ ƚŚĞ ƌĞĂĐƟŽŶ ŽĐĐƵƌƐ ĞǀĞŶ ŝŶ By the action of conc. sulphuric acid on metal chlorides
ĚĂƌŬ͘ Most metal chlorides when reacted with conc. sulphuric acid (H SO ) give
4
2
hydrogen chloride, and metal sulphate or metal bisulphate depending
upon the temperature. For example,
below 200°C
NaCl(s) + H SO o NaHSO (s) + HCl(g)
2
4
4
sodium chloride conc. sulphuric acid sodium bisulphate hydrogen chloride
above 200°C
2NaCl(s) + H SO o Na SO (s) + 2HCl(g)
4
2
2
4
sodium chloride conc. sulphuric acid sodium sulphate hydrogen chloride
Laboratory Preparation of Hydrogen Chloride
How is hydrogen chloride prepared in laboratory
Hydrogen chloride is prepared in the laboratory by heating a mixture of
sodium chloride (or common salt) and concentrated sulphuric acid in a
TQWPF DQVVQO ƀCUM *%N ICU KU EQNNGEVGF D[ WRYCTF FKURNCEGOGPV QH CKT