Question

Oxidation number of sodium in sodium amalgam is:
A) +2
B) +1
C) -3
D) 0

Answer 1

Amalgam is considered to be the alloy which contains mercury as its constituent. It can be liquid or solid or a soft paste and that depends on the proportion of the mercury that has been mixed. It is a restorative material and an inexpensive substance. The commonly used dental amalgam consists of silver and mercury.

Complete step-by-step answer:
Oxidation number is defined as the charge which is present on the atom which appears to form the ionic bonds with other heteroatoms. The atom which has the high electronegativity has the negative oxidation state. The ionic bonding is formed by the sharing or transferring of electrons.

The sodium amalgam is made up of sodium and mercury. We should follow the chemical reactions by looking at changes in the oxidation number of the atom in each compound during the reaction because the oxidation number helps in determining the nomenclature of the compounds. The oxidation number is the charge which the atom has when the compound is composed of ions.

The amalgams are the mixtures but they are not compounds. So this concludes that there is no chemical combination between sodium and mercury. So the oxidation state of the metal in amalgam is always zero.

So the correct answer is option ‘D’.

Note: The oxidation state of any element in its free state is always zero. If the charge on the ion is high then it will be difficult to remove the electron from it so it will have higher ionization energy. The oxidation state of the atom in the homo polar molecule is zero.