Question

(a) Differentiate between soap and detergents.
(b) Why pure acetic acid is called glacial acetic acid.
(c) What is covalent bond? Write two properties of covalent compounds.

Answer 1

For the soaps and detergents, we have the hydrophilic and hydrophobic part in the compound, which affects its reaction in water.
For the acetic acid, when there is less than a percent of water in it, it solidifies easily due to lowering of its melting point.
In the covalent bonding, it shows the sharing of the bonded electron pair between the two atoms, having a slight electronegative difference.

Complete step by step answer:
a) Soaps and detergents
- Soaps are the sodium salts of the long aliphatic chain of carboxylic acid, whereas in the detergents, it is the sodium salt of the long alkyl chain of sulfonic acid.
- The soaps are prepared from the saponification of the plant oils and animal fat, thus are easily biodegradable. Whereas, the detergents are formed from the hydrocarbon of petroleum or coal, and are non-biodegradable in nature.
- In the soaps, due the presence of the carboxylic group at the end of the long aliphatic chain, they are highly water-loving in nature, but their effectiveness reduces in the hard water, where they react with the calcium and magnesium ions present in the hard water.
In case of the detergents, the hydrophilic part does not react with the ions present in the hard water. Thus, they are highly effective in producing lather in both the plain and the hard water.
-Example of soaps is sodium stearate $({{C}_{17}}{{H}_{35}}CO{{O}^{-}}N{{a}^{+}})$ and sodium palmitate $({{C}_{15}}{{H}_{31}}CO{{O}^{-}}N{{a}^{+}})$, whereas the detergents is sodium lauryl sulphate or sodium n-dodecyl sulphate $({{H}_{25}}{{C}_{12}}-O-S{{O}_{2}}-{{O}^{-}}N{{a}^{+}})$.

b) The solution of acetic acid in which it is highly concentrated with acetic acid and free from water molecules in it. Thus, also known as the anhydrous acetic acid. This enhances the solidification of the acid as its melting point reduces to ${{16.7}^{\circ }}C$ , which is lower than the normal room temperature and converts to ice readily. Therefore, this undiluted acetic acid is known as the glacial acetic acid.

c) When the valence electrons in the atom share its electrons with the neighbouring atoms, in order to complete it octet. This equal sharing of the electrons between the two atoms, having stable electrostatic force leads to the formation of a weak bond called the covalent bond.
Properties of the covalent bonds are:
- Being a weak interaction, it is easy to overcome it with a small amount of energy. Thus, leading to its lower melting and boiling point.
- Also, the covalent bonding present in solids makes them soft or brittle as the interactive force between the atoms is weak. They even show poor conductivity as they are not so ionic in nature.

Note: The soaps and detergents, during the cleaning of clothes, undergo micelles formation to trap the dirt molecules.
- In the anhydrous acetic acid, it is highly corrosive in nature and can burn the skin.
- In the covalent bonding, there is no free electron present or charge over the molecule, due to which there is poor conductivity.