Question

Write the empirical formula for at least four ionic compounds that could be formed from the following ions: Fe2+,Cr4+,Cl-,O2-

Answer 1

Answer: Four ionic compounds formed will be $FeCl_2,FeO,CrCl_4\text{ and }CrO_2$

Explanation:

Ionic compound is formed by the complete transfer of electrons from 1 atom to another atom. The cation is formed by the loss of electrons by metals and anions are formed by gain of electrons by non metals.

We are given:

Two cations having formulas $Fe^{2+}\text{ and } Cr^{4+}$

Two anions having formulas $Cl^-\text{ and }O^{2-}$

By criss-cross method, the oxidation state of the ions gets exchanged and they form the subscripts of the other ions. This results in the formation of a neutral compound.

The four ionic compounds are:

• When iron ion and chloride ions combine, it results in the formation of $FeCl_2$ compound. This is named as iron (II) chloride.
• When iron ion and oxide ions combine, it results in the formation of $FeO$ compound. This is named as iron (II) oxide.
• When chromium ion and chloride ions combine, it results in the formation of $CrCl_4$ compound. This is named as chromium (IV) chloride.
• When chromium ion and oxide ions combine, it results in the formation of $Cr_2O_4=CrO_2$ compound. This is named as chromium (IV) oxide.

Hence, the four ionic compounds formed will be $FeCl_2,FeO,CrCl_4\text{ and }CrO_2$