Question

Lunar caustic is:
A.AgCl
B.$AgN{{O}_{3}}$
C.ZnOH
D.None of these.

Answer 1

The word “lunar” part comes from the earliest beliefs of alchemists, who associated the element silver with the Moon.
It is called “caustic” because it is corrosive and irritates the various tissues of the body.

Complete answer:
1. Silver nitrate is known as lunar caustic.
2. Silver nitrate particularly when fused and molded into sticks to use as caustic.
3. Silver nitrate is an inorganic compound with chemical formula ($AgN{{O}_{3}}$)
4. $AgN{{O}_{3}}$salt is a multipurpose precursor to many other silver compounds, for example those used in photography.
5. $AgN{{O}_{3}}$is far less sensitive to light than the halides.
Therefore lunar caustic means Silver nitrate.

So, the correct answer is B.

Additional information:
Properties of silver nitrate:
- $AgN{{O}_{3}}$ as a colorless in appearance in its solid state and it is odourless.
- The structure of $AgN{{O}_{3}}$in crystal state is orthorhombic.
- Silver nitrate is toxic and corrosive in nature.
- The reaction of silver nitrate with ethanol is explosive.
- The silver present in silver nitrate is displaced by copper easily and converts into copper nitrate.
- $2AgN{{O}_{3}}+Cu\to Cu{{(N{{O}_{3}})}_{2}}+2Ag$

Uses of silver nitrate:
- When dilute silver nitrate with water to a concentration of 0.5%, it can serve as an antiseptic in many medical setups.
- Mixtures of alkenes can be separated with the help of silver nitrate, since the silver cation in silver nitrate attaches with alkenes in a reversible fashion.
- In inorganic chemistry, halides are extracted with the help of silver nitrate.

Note: When heated silver nitrate at 440$^{o}C$, it completely decomposes to give oxygen, nitrogen dioxide, and silver.
$2AgN{{O}_{3}}\xrightarrow{{{440}^{o}}C}2Ag+{{O}_{2}}+2N{{O}_{2}}$
Due to the ability of this compound to form a precipitate of silver halides when treated with halide ions, it is used while making photographic films.
$2AgN{{O}_{3}}+C{{l}_{2}}\xrightarrow{{{440}^{o}}C}2AgCl\downarrow +{{O}_{2}}+2N{{O}_{2}}$