# Why is CuSO_3 called copper (II) sulfite?

Nov 22, 2017

The Copper comes from the Cu in the formula. The (II) comes from the oxidation number of the copper in the complex. The Sulfite comes from the $S {O}_{3}$ ion.

Nov 22, 2017

Because it is the salt of $\text{sulfurous acid}$...${H}_{2} S {O}_{3}$ NOT $\text{sulfuric acid}$, ${H}_{2} S {O}_{4}$.......

#### Explanation:

The salts of $\text{sulfuric acid}$ are called $\text{sulfates}$....in which sulfur assumes the $S \left(V I +\right)$ oxidation state...

On the other hand, the salts of $\text{sulfurous acid}$, ${H}_{2} S {O}_{3}$, are called $\text{sulfites}$,....in which sulfur assumes the $S \left(I V +\right)$ oxidations state...The counterion is $S {O}_{3}^{2 -}$...

And the salts of $\text{hydrogen sulfide}$ are called $\text{sulfides}$, the analogue of oxides, and here we gots $S \left(- I I\right)$....

Sometimes we represent ${H}_{2} S {O}_{3}$ as ${H}_{2} O \cdot S {O}_{2}$, i.e. water saturated with $S {O}_{2}$. The smell of sulfurous acid is sulfurous, but many people, including me, find the smell pleasant, and clean, and antiseptic.

So finally, $C u S {O}_{4} \equiv \text{copper sulfate}$, and $C u S {O}_{3} \equiv \text{copper sulfite}$, and $C u S \equiv \text{copper sulfide}$. And in each salt we gots $C {u}^{2 +}$, $\text{cupric ion}$.