Question

Give scientific reason: Common salt has high melting point and boiling point

Answer 1

Hint: The chemical name of common salt is Sodium chloride (NaCl). It is a metal halide made up of sodium and chloride. NaCl appears as a white crystalline solid at normal room temperature.

Complete step by step solution:

Before we go on answering, we need to have an understanding of Ionic compounds and Ionic bonding.
Ionic compounds are compounds made up of positive ions (cations) and negative ions (anions) which are held together by strong electrostatic forces in a rigid array or lattice.
Electrostatic attraction between the cations and anions is referred to as Ionic bonding.

Ionic compounds show very interesting physical properties. One of the major physical properties is that they have a high melting and boiling points. This happens because there is a strong electrostatic force of attraction between the oppositely charged ions. In other words, the Ionic bonding is very strong. As a result, it requires a large amount of energy to overcome this attraction in order to allow the ions to move more freely and form a liquid.
Sodium chloride is also a type of Ionic compound. Both Sodium cation (\[N{{a}^{+}}\]) and Chloride anion (\[C{{l}^{-}}\]) form a strong ionic bonding which takes a lot of energy to break.

Hence, the high melting and boiling point.

Note: To be more specific, the factors governing the melting point of an ionic compound are:
The charge on the ions
As a general rule, the greater the charge, the greater the electrostatic attraction, the stronger the ionic bond, the higher the melting point.
Size of the ions
Smaller ions can pack closer to each other than the larger ions. As a result, the electrostatic attraction is greater, the ionic bond is stronger, the melting point is higher.