Question

Which of the following is a soap?
A) ${C_{17}}{H_{35}}{C_6}{H_4}S{O_3}Na$
B) $C{H_3}COONa$
C) ${C_{17}}{H_{35}}COONa$
D) ${C_3}{H_8}{O_3}$

Answer 1

Hint: Soaps are made by the process of saponification which converts fat oil into soap by the action of heat in the presence of alkali $\left( {NaOH} \right)$ . Fatty acids are molecules of a long chain of carbon atoms of at least 10 carbon atoms and the general formula of soap is $RCO{O^ - }N{a^ + }$ where R is an alkyl group.

 Complete step by step answer:
Soaps are salts of fatty acids and fatty acids are molecules consisting of long chains of lipid-carboxylic acid found in fats and oils and in cell membranes as a component of phospholipids and glycolipids. The eight fatty acids that make up soap molecules include four saturated fatty acids – myristic, lauric, palmitic and stearic and four unsaturated fatty acids are ricinoleic, oleic, linoleic and linolenic. Each fatty acid is saponified and creates a sodium or potassium salt of a fatty acid or a soap. Hence, option D can’t be correct. Soaps are fatty acids and fatty acids are long chains of carbon atoms i.e., at least 10 carbons. Thus, option B is also not correct.
Saponification is a process that involves the conversion of fat, oil or lipid into soap by the action of heat in the presence of aqueous alkali such as NaOH. Soaps are represented by the general formula $RCO{O^ - }N{a^ + }$where R denotes alkyl groups consisting of 12 to 18 carbon atoms. Thus, option C is correct and the name of the compound is sodium stearate. It is the sodium salt of stearic acid. This is the most common type of soap. It is found in many types of solid deodorants, latex paints etc. The percentage of sodium stearate depends on the ingredient fats. Purified sodium stearate can be made by neutralizing stearic acid with sodium hydroxide.
Therefore, option C is correct.

Note: Remember that soaps are salts of fatty acids that are molecules of long chains of carbon atoms with at least 10 carbon atoms attached to each other and it is made by the reaction between sodium hydroxide and stearic acid which results in the formation of sodium stearate (soap).