Silver nitrate or Lunar caustic (AgNO3)
Silver nitrate is prepared by dissolving silver in dilute nitric acid.
3Ag + 4HNO3 ® 3AgNO3 + 2H2O + NO
1. It is soluble in water.
2. Its aqueous solution may decompose on exposure to light.
1. Action of Heat
On heating AgNO3 decomposes in two stages
2A gN O 3 --- 723 K -- > 2A gN O 2 + O 2 S ilv er n itrite
A gN O 2 --- 980 K -- > Ag + NO2
2. With NaCl
AgNO3 gives white precipitate of AgCl with soluble ionic chlorides.
AgNO3 + NaCl ® AgCl¯ + NaNO3
Silver nitrate is strongly caustic and oxidizing in nature.
4. With KBr & KI
AgNO3 gives pale yellow precipitate of AgBr with bromides and yellow AgI with iodides.
AgNO3 + KBr ® AgBr + KNO3
AgNO3 + KI ® AgI + KNO3
5. Action with organic compounds
Ammoniacal silver nitrate (Tollen's reagent) is reduced to silver mirror by
compounds like formic acid, formaldehyde or glucose
2AgNO3 + 2NH4OH ® Ag2O + 2NH4NO3 + H2O
Ag2O + HCOOH ® 2Ag¯ + H2O + CO2
1. It is used in the preparation of silver halides which are extensively used in
3. It is used in silvering mirrors.
4. It is used in preparation of marking inks and hair dyes. It is used for silver plating.
5. It is used as laboratory reagent.