Question

Dry distillation of a mixture of calcium acetate and calcium formate forms:
A. methanol
B. ethanal
C. ethanol
D. acetone

Answer 1

Hint: Calcium acetate is the calcium salt of acetic acid with chemical formula \[Ca{\left( {{C_2}{H_3}{O_2}} \right)_2}\]. It is also known as calcium ethanoate and acetate of lime. It is a white hygroscopic solid having a slight odour of acetic acid.

Complete answer
When calcium carbonate or hydrated lime undergoes reaction with vinegar, calcium acetate is obtained.
\[CaC{O_3} + 2C{H_3}COOH{\rm{ }} \to Ca{\left( {C{H_3}COO} \right)_2} + {H_2}O + C{O_2}\]
Similarly, calcium formate is the calcium salt of formic acid with chemical formula \[Ca{\left( {HC{O_2}} \right)_2}\]. It also has a slight odour of acetic acid. It is also known as calcium methanoate and calcoform.
Dry distillation of a mixture of the above calcium salts of acetic and formic acid respectively leads to the formation of an aldehyde. Dry distillation is the process in which the solid materials are heated to produce gaseous products. A mixture of calcium acetate and calcium formate undergoes dry distillation i.e. when heated produces an aldehyde called ethanol or acetaldehyde.
\[Ca{\left( {OCOC{H_3}} \right)_2} + Ca{\left( {OCOH} \right)_2} \to 2C{H_3}CHO + 2CaC{O_3}\]
In this reaction the alkyl parts are derived from the different carboxylic acids involved i.e. alkyl part has been derived from the acetate and the aldehyde part has been derived from the formate.

Hence, option (B) ethanal, is the correct option.

Note:
Thus, when a mixture of calcium acetate and calcium formate undergoes dry distillation, ethanal is produced. This is because when calcium salts of carboxylic acids are heated by mixing them together they form either aldehyde or ketone. The alkyl parts of the ketone or aldehyde produced is derived from the different carboxylic groups involved.