please why Na2Co3 is called sodium carbonate (iv).i do not understand why the (iv) is mention and also H2So4,how come about the (vi) in the name (tetraoxosulphte (vi) acid
the iv and the vi refer to the oxidation state of Sulfur, and carbon in the compounds. For these two, it is most unusual to put the roman numerals in the name.
To follow up on Bob Pursley's answer, the iv and vi are unnecessary. Technically, I think it is wrong; however, everyone will know what it means.
The notation of (iv) or (vi) in the names of chemical compounds refers to the oxidation state of the central atom within the compound.
In the case of Na2CO3, sodium carbonate, the (iv) indicates the oxidation state of the carbon atom. Carbon typically has an oxidation state of +4 in sodium carbonate. This means that the carbon atom within the compound is contributing four electrons towards the overall charge of the compound.
Similarly, in the case of H2SO4, sulfuric acid, the (vi) indicates the oxidation state of the sulfur atom. Sulfur typically has an oxidation state of +6 in sulfuric acid. This means that the sulfur atom within the compound is contributing six electrons towards the overall charge of the compound.
To determine the oxidation state of an element within a compound, you can use various rules based on the molecule's overall charge and the electronegativity of the other elements involved. The rules for determining oxidation states in simple compounds include:
1. For atoms in their elemental state, the oxidation state is zero.
2. The sum of the oxidation states in a neutral compound is zero.
3. The sum of the oxidation states in a polyatomic ion is equal to its charge.
By following these rules and considering the electronegativity and known oxidation states of the elements involved, you can determine the oxidation state of specific elements within a compound.