Question

Corrosive sublimate $(HgC{l_2})$ can be used to distinguish between:
A.Formaldehyde and propanone
B.Formic acid and acetic acid
C.Acetaldehyde and butanone
D.All of the above

Answer 1

We have to know that the corrosive sublimate $(HgC{l_2})$ (also known as perchloride of mercury, mercuric chloride, mercury$(II)$chloride)is a white solid. Mercuric chloride exists not as salt composed of discrete ions, but rather consists of linear triatomic molecules, hence its tendency to sublime. Mercuric chloride is also a chemical reagent used in organic synthesis and analytical chemistry.

Complete step by step answer:
We need to remember that a substance capable of destroying or eating away by chemical reaction or having a tendency to create corrosion is known as a corrosive substance. Sublime could be connected to the term of the sublimate. As we know that the sublime is the process, a substance which can undergo directly solid into gas is called sublimation. Whereas sublimate is the residue left behind after sublimation.
One of the preparation of mercuric chloride is,
$Hg + C{l_2} \to HgC{l_2}$
Mercury readily combines with chloride to give mercuric chloride.
Corrosive sublimate $(HgC{l_2})$ reaction with formic acid to give calomel (mercurous chloride, mercury $(I)$chloride), $Hg{}_2C{l_2}$ , hydrochloric acid and liberation of carbon dioxide. The chemical reaction is,
$HCOOH + 2HgC{l_2} \to 2H{g_2}C{l_2} \downarrow + 2HCl + CO2 \uparrow$
$Hg{}_2C{l_2}$ (Mercury$(I)$chloride) is obtained as white precipitate in the above chemical reaction and formic acid acts as a reducing agent, reduces mercury $(II)$ chloride to mercury $(I)$ chloride.
But acetic acid is not affected, when reaction with corrosive sublimate $(HgC{l_2})$, and it does not show any reducing property.
Corrosive sublimate $(HgC{l_2})$ can be used to distinguish between formic acid and acetic acid,
So, Option B. formic acid and acetic acid is the correct option.

Note:
We must remember that the mercuric chloride is a highly corrosive and toxic substance. Mercuric chloride was used as a treatment for syphilis, it’s now not used for meditative functions due to the toxicity of mercury and therefore the convenience of superior treatments. Mercuric chloride is used in photography, disinfectants and also used as wood preservative.