Question

The bond of Hg-Cl is more ionic in $HgC{l}_2$ than that in $H{g}_{2}C{l}_2$
(A) True
(B) False

Answer 1

Hint: We can predict the ionic or covalent character of a bond in the given inorganic compound by Fajan’s rules. It is related to the size and the charge on the cations and the anions forming the molecule.

Complete step by step solution:
Here, we are given two compounds, $HgC{l}_2$ (Mercuric chloride) and $H{g}_{2}C{l}_2$ (Mercury dichloride). We need to find which of the given compounds will have a more ionic character for the Hg-Cl bond.
-We can see that Hg-Cl bond exists in both the compounds. Here, the oxidation state or formal charge on the mercury ions is not the same. So, that will affect the character of the Hg-Cl bond.
-Scientist Fajan gave some rules by which we can predict the ionic or covalent character of the bond. The rules are here.
-He stated that in the case of the cations, the smaller size favours covalent character and larger size favours ionic character of the bond. In the case of anions, the smaller size favours ionic character and larger size favours covalent character. He also added that as the charge on the cation increases, the covalent character increases.
-In given compounds, we can see that anions are the same. Cations are also of mercury element but they have differences in oxidation states.
-In $HgC{l}_2$, Hg is in +2 state and in $H{g}_{2}C{l}_2$, Hg is in +1 oxidation state. So, we can predict according to Fajan’s rules that the ions which have lower oxidation states will have the more ionic character of the bond.
-Thus, we can say that the Hg-Cl bond will be more ionic in $H{g}_{2}C{l}_2$ than in $HgC{l}_2$.

So, the statement given in the question is false and the correct answer is (B).

Note: Do not assume that both anions and cations are the same in $HgC{l}_2$ and $H{g}_{2}C{l}_2$. Actually, the oxidation state of Hg atoms is different in both the given compounds and the difference in oxidation state will affect the ionic character of the compound.