Question

When a mixture of Calcium Benzoate and Calcium formate is dry distilled we get:
A. Formaldehyde
B. Acetaldehyde
C. Benzaldehyde
D. Salicylaldehyde

Answer 1

Hint: In the method of dry distillation solid materials are heated to form gaseous products. This method involves the thermolysis or pyrolysis process. Dry distillation method is used to produce liquid fuel from wood and coal.

Complete step by step answer:
Let’s understand the method of dry distillation in detail. In this method a solid material is strongly heated in absence of air. By applying this method, decomposition of organic matter to liquid or gas takes place which ultimately volatilizes and part of such liquid or gas remains a solid matter. Let’s understand the dry distillation of rubber. Due to dry distillation of rubber, rubber substance and oil substance decomposes and vaporizes and the carbon black remains as recycled carbon black (solid).
Now, come to the question. We have to identify the product obtained on dry distillation of a mixture of calcium benzoate and calcium formate. Dry distillation of calcium benzoate and calcium formate produces formaldehyde. The chemical reaction is shown as follows:

$\left ( Ph-COO- \right )_{2}Ca+\left ( H-COO- \right )_2Ca\overset{Heat}{\rightarrow}2Ph-CHO+2CaCO_{3}$
                                                                                    $\text{ Benzaldehyde}$

So, the correct answer is Option A.

Additional Information:
Distillation is a technique used in purification of liquid or separation of liquid components from a mixture. In this process, the liquid is heated to its boiling point to result in vapor and again condensing vapor into liquid.

Note: It is to be noted that when substances of vegetable origin such as wood, coal, petrol etc. are dry distilled, they decompose into liquid products, gas and coal/charcoal. The chemical nature of decomposition products depends on the conditions under which dry distillation takes place and the nature of the raw material.