Question

The product formed by heating a mixture of ammonium chloride and potassium cyanate is
A.\[{{\rm{N}}_{\rm{2}}}{\rm{O}}\]
B.\[{\rm{N}}{{\rm{H}}_{\rm{3}}}\]
​C.\[{\rm{C}}{{\rm{H}}_{\rm{3}}}{\rm{N}}{{\rm{H}}_{\rm{2}}}\]
​D.\[{{\rm{H}}_{\rm{2}}}{\rm{NCON}}{{\rm{H}}_{\rm{2}}}\]

Answer 1

Hint: The treatment of ammonium chloride with potassium cyanate gives ammonium cyanate. Ammonium cyanate under the action of heat forms urea.

Complete Step by Step Solution:
When a mixture of ammonium chloride and potassium cyanate is heated, they form ammonium cyanate.
The chemical formula of ammonium cyanate is
NH₄CNO.

The reaction happens as follows:
\[{\rm{N}}{{\rm{H}}_{\rm{4}}}{\rm{Cl + KCNO}} \to {\rm{N}}{{\rm{H}}_{\rm{4}}}{\rm{CNO}}\]
Ammonium cyanate is a salt which occurs only as a weak intermediate.
Ammonium cyanate breaks down to ammonia and cyanic acid.
The chemical formula for cyanic acid is HOCN.
Ammonia and cyanic acid together form urea.
This is a reversible reaction.
This reaction is called Wohler's synthesis.

Image: Formation of urea

Out of the given options, option D is the chemical formula of urea.
So, option D is correct.

Additional Information: The Wöhler synthesis is the transformation of ammonium cyanate into urea. This chemical reaction was depicted in 1828 by Friedrich Wohler. It is frequently referred to as the beginning step of modern organic chemistry. Around 1780 chemists began to differentiate between organic compounds collected from
plants and animals and inorganic compounds readied from mineral sources. Berzelius, a Swedish chemist formulated that a ‘vital force’ was credible for the building of organic compounds. However, this belief was dismissed in 1828 when F. Wohler synthesise an organic compound, urea from an inorganic compound, ammonium cyanate.
There are different chemical names for urea like diaminomethanal, carbamide, carbonyl diamide, etc., but urea is the preferred IUPAC name.

Note: While attending to the question, one must have an idea about Wohler's synthesis reaction. The chemical formula of urea must be kept in mind while going through the given options.