Chemistry XII Content





Silver Nitrate (AgNO3)

Silver Nitrate is commonly     known as Lunar caustic.
 
 Preparation
AgNO3 is prepared by dissolving silver metal in dil HNO3. The silver nitrate solution of crystallization gives colorless crystal of AgNO3.
3Ag + 4HNO3          →              3AgNO3 + NO + 2H2O.

Properties

It is colorless crystalline solid soluable in water.
It is highly sensitive to light and when kept in contact with skins it leaves a permanent dark stain.

Action of heat.
When silver nitrate is heated first it decompose forming silver nitrite which on further heating decompose giving silver metal.
2AgNO3                →                  2AgNO2 + O2
AgNO2                    →                  Ag + NO2
 
Precipitation reaction
AgNO3 gives precipitate with halide ion (Cl,  Br  & I  ) and from color of precipitate the halide ion can be identified.
Cl  + AgNO2          →                 AgC + NO3
Curdy white
Br  + AgNO2              →             AgBr + NO3
Pale yellow
I  + AgNO2           →                  AgI + NO3
Yellow ppt
Ammonical Silver Nitrate [Tollen’s reagent] is used to detect reducing groups in organic compounds like aldetyde. The reducing agent reduces tollen’s reagent to metallic silver which deposits in test-tube forming silver mirror.
Ag2O + HCHO               →                    2Ag + HCOOH
Toller’s reagent

Uses

i. it is used in makingsilver halides used in photography.
ii. It is used in making inks and hair dye’s.
iii. It is used in making silver mirror.
iv. It is used in lab as analytical reagent.

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