Question

The formula of tetrachloromethane is:
A) $\text{CCl}{{\text{H}}_{\text{3}}}$
B) \[\text{CC}{{\text{l}}_{\text{2}}}\]
C) $\text{CHC}{{\text{l}}_{\text{3}}}$
D) $\text{CC}{{\text{l}}_{\text{4}}}$

Answer 1

Hint: Tetrachloride methane is an organic compound. As the name suggests it must be methane like structure and tetra suggests there are four chlorine atoms on the carbon. Thus the only possibility remaining is where each of the hydrogens of methane is replaced by the chlorine.

Complete answer:
Here we use the IUPAC rules of nomenclature to get the structure of tetrachloromethane.-
Since here we know the name of the structure and we have to determine the molecular formula.
The IUPAC name of the organic compound is represented as:
$\text{Prefix+Word root + Primary suffix + Secondary suffix}$
In tetrachloromethane
$\begin{align}
  & \text{No of prefix =4 (tetra)} \\
 & \text{Prefix = Chloro} \\
 & \text{Word root = Meth} \\
 & \text{Primary suffix =ane} \\
 & \text{Secondary suffix = -} \\
\end{align}$
Thus from the above data, we know that it is methane\[\text{C}{{\text{H}}_{\text{4}}}\],
\[\begin{align}
  & \begin{matrix}
   {} & {} & \text{H} & {} & {} \\
   {} & {} & \text{ }\!\!|\!\!\text{ } & {} & {} \\
   \text{H} & \text{-} & \text{C} & \text{-} & \text{H} \\
   {} & {} & \text{ }\!\!|\!\!\text{ } & {} & {} \\
   {} & {} & \text{H} & {} & {} \\
\end{matrix} \\
 & \\
\end{align}\]
Like structure. It has 4 chloro group which is possible only when the 4 hydrogens in methane are replaced by chlorine as follows:
\[\begin{align}
  & \begin{matrix}
   {} & {} & \text{Cl} & {} & {} \\
   {} & {} & \text{ }\!\!|\!\!\text{ } & {} & {} \\
   \text{Cl} & \text{-} & \text{C} & \text{-} & \text{Cl} \\
   {} & {} & \text{ }\!\!|\!\!\text{ } & {} & {} \\
   {} & {} & \text{Cl} & {} & {} \\
\end{matrix} \\
 & \\
\end{align}\]
Thus condensed for the molecular formula tetrachloromethane is\[\text{CC}{{\text{l}}_{\text{4}}}\].

Hence, (D) is the correct option.

Additional information:
In tetrachloride, methane means four hydrogens in methane replaced by the chlorine. Thus the molecular formula will be: \[\text{CC}{{\text{l}}_{\text{4}}}\]
The central carbon atom is surrounded by four chlorine atoms. The carbon has four valence electrons. Each chlorine atom contains the seven valence electrons in its outermost shell. To attain the Noble gas configuration it requires one electron. The carbon and the chlorine share its electron to form a covalent bond between the carbon and chlorine.
The Lewis dot structure for carbon tetrachloride is as follows:
\[\begin{matrix}
   {} & : & \overset{..}{\mathop{Cl}}\, & : & {} \\
   .. & {} & | & {} & .. \\
   :Cl & - & C & - & Cl \\
   .. & {} & | & {} & .. \\
   {} & : & \underset{..}{\mathop{Cl}}\, & : & {} \\
\end{matrix}\begin{matrix}
   {} \\
   : \\
   {} \\
\end{matrix}\]
Since there are four atoms bonded to the carbon atom. The \[\text{CC}{{\text{l}}_{\text{4}}}\] is $\text{s}{{\text{p}}^{\text{3}}}$ hybridized. Thus the molecular geometry \[\text{CC}{{\text{l}}_{\text{4}}}\]is tetrahedral. There are the same atoms around the carbon atom; it is non-polar.
In carbon tetrachloride molecules, the chlorine atoms are at the corners of the tetrahedral configuration. It is a volatile substance.

Note:
The trichloromethane is commercially known as the carbon tetrachloride. It has wide applications as a solvent. Remember the simple rules for the IUPAC nomenclature.