Page 243 - Chemistry ICSE Class X

Study of Compounds–Ammonia 229
ƒ With acids. Ammonia being basic in character, reacts with acids to
form salts. For example,
NH (g) + HCl(conc.) o NH Cl(s)
3
4
ammonia hydrochloric ammonium chloride
(base) acid (acid) (white fumes)
2NH (g) + H SO (aq) o (NH ) SO (aq)
3
4 2
4
2
4
ammonia sulphuric acid ammonium sulphate
(base) (acid) (salt)
NH (g) + HNO (aq) o NH NO (aq)
3
4
3
3
ammonia nitric acid ammonium nitrate
Crystalline ammonium nitrate and ammonium sulphate are used as
fertilizers.
ƒ With metal oxides. When passed over heated metal oxides, ammonia
gets oxidised to nitrogen and reduces metal oxide to metal.
hot
3CuO + 2NH (g) o 3H O + N 2 + 3Cu(s)
2
3
copper(II) oxide nitrogen copper
3PbO + 2NH (g) o 3H O + N (g) + 3Pb(s)
2
2
3
lead(II) oxide nitrogen lead
ƒ With halogens. Ammonia reacts with halogens and the nature of
products depends upon the halogen and the reaction conditions.
ŵŵŽŶŝƵŵ ĐŚůŽƌŝĚĞ ŝƐ ĂŶ ĞdžĂŵƉůĞ
Š With chlorine. With limited amount of chlorine, nitrogen and ǁŚĞƌĞ ƚǁŽ ĐŽůŽƵƌůĞƐƐ ŐĂƐĞƐ͕ , ů ĂŶĚ
ammonium chloride are formed, while in the presence of excess of E, ͕ ƌĞĂĐƚ ƚŽ ĨŽƌŵ Ă ǁŚŝƚĞ ƐŽůŝĚ ĚŝƌĞĐƚůLJ͘
3
chlorine, nitrogen trichloride is formed. ͻ
ŵŵŽŶŝƵŵ ĐŚůŽƌŝĚĞ ƐƵďůŝŵĞƐ ŽŶ
0 * 3 + 3Cl (limited) o 6NH Cl + N 2 ŚĞĂƟŶŐ͘
2
4
ammonia (excess) chlorine E, ů;sͿ E, ů;gͿ E, ů;s)
4
4
4
Products. Ammonium chloride, Nitrogen.
Observation. The greenish-yellow colour of chlorine disappears,
and white fumes of ammonium chloride are seen.
NH 3 + 3Cl (excess) o NCl 3 + 3HCl
2
chlorine nitrogen trichloride
Products. Hydrogen chloride and yellow-coloured highly explosive
liquid called nitrogen trichloride. This reaction shows that chlorine
JCU ITGCV CHſPKV[ HQT J[FTQIGP CPF VJCV COOQPKC KU C TGFWEKPI
agent.
Š With bromine. Ammonia with bromine gives ammonium bromide
and nitrogen.
0 * 3 + 3Br o 6NH Br + N 2
4
2
Š With iodine. When rubbed with solid iodine, a dark-coloured
precipitate of nitrogen tri-iodide is obtained. ŵŵŽŶŝƵŵ ŶŝƚƌŝƚĞ ĐĂŶ ĂůƐŽ ďĞ ƵƐĞĚ
ƚŽ ƉƌĞƉĂƌĞ ŶŝƚƌŽŐĞŶ ;E Ϳ͘
2
2NH (aq) + 3I (s) o NH NI (s) + 3HI E, EK ;sͿ o E ;gͿ н Ϯ, K;g)
'
3
3
3
2
2
4
2
2
On drying, NI when struck with a hammer or against a hard
3
surface explodes producing iodine vapour.
pressure
0 * 3 .NI o 5N 2 + 9I 2 + 6NH I
4
3
ƒ With carbon dioxide (formation of urea). Ammonia when heated
under pressure with CO gives urea.
2
u%
2NH (g) + CO (g) o NH CONH (s) + H O
2
2
3
2
2
Ō CVO
urea
ƒ Action with solutions of heavy metal ions. With the solutions
containing metal ions of Al, Fe, Cr and Zn, ammonia forms coloured
metal hydroxides which are insoluble and form precipitates.