Question

How do you write the formula for chromium(III) sulfide?

Answer 1

Hint: The chemical formula of Chromium(III) sulfide is found by using the concept of the valency of the atom which is the capacity of any substance to gain/lose the electron. Valency of Cr is +3 and that of the S is -2. Now, find the chemical formula.

Complete answer:
Chromium(III) sulfide is an inorganic compound and it consists of the elements chromium and Sulphur and Chromium(III) sulfide is formed by the action of the Sulphur on the chromium and
We can find the formula of Chromium(III) sulfide by using their valency i.e. on the basis of their tendency to lose or gain the electrons.
In Chromium(III) sulfide , Chromium atoms have +3 charge on it. It means that the chromium atom loses three electrons from its valence shell and thus exhibits +3 oxidation state in Chromium(III) sulfide and so, its valency is +3. On the other hand, Sulphur has a tendency to gain two electrons and thus exhibits -2 oxidation state in their compounds and so, its valency is -2.
So, the chemical formula of Chromium(III) sulfide is:
                              Cr S
                               3 2
On cross multiplication, 2 with Cr and 3 with S, the chemical formula of the Chromium(III) sulfide turn out to be- $\text{C}{{\text{r}}_{2}}{{\text{S}}_{3}}$.

Note:
Chromium sulfide is the compound which is brownish-blackish in color and is solid and odorless in nature and it has the molar mass as $200.19\text{ g mol}{{\text{e}}^{-1}}$. It is insoluble in water and has the density of $3.77\text{ g c}{{\text{m}}^{-3}}$.