Question

In the reaction, \[Fe + 2HCl \to FeC{l_2} + {H_2}\]. What is the oxidation state of \[Fe\] in \[FeC{l_2}\]?
A. \[ + 2\]
B. \[ + 3\]
C. \[ + 4\]
D. \[ + 5\]

Answer 1

Hint: We need to know that the iron is the chemical element having the atomic number \[26\]. The iron is a metal which belongs to the first transition series. The belonging group and period are eight and four respectively. The hydrochloric acid is a strong acid having the formula, $HCl$. The elements present in the compound are hydrogen and chlorine. The ferrous chloride is also known as iron (II) chloride which is a chemical compound with formula, \[FeC{l_2}\].

Complete answer:
The given chemical reaction undergoes both oxidation and reduction reaction. Hence, it is a redox reaction. In this reaction, \[Fe + 2HCl \to FeC{l_2} + {H_2}\], hydrochloric acid acts as the oxidizing agent and iron acts as a reducing agent.
The oxidation – reduction can be written as,
\[2{H^I} + 2{e^ - } \to 2{H^0}\left( {Oxidation} \right)\]
\[F{e^0} - 2{e^ - } \to F{e^{II}}\left( {\operatorname{Re} duction} \right)\]
The oxidation state of chloride ions in ferrous chloride is \[ - 1\]. Let ‘X’ be the oxidation state of iron in \[FeC{l_2}\]. Hence, the oxidation state of iron in \[FeC{l_2}\] can be found out by substituting the value of oxidation state of chloride ion in \[FeC{l_2}\].
\[X + 2\left( { - 1} \right) = 0\]
$X - 2 = 0$
$ \Rightarrow X = 0$
Therefore, the oxidation state of iron in \[FeC{l_2}\] is equal to \[ + 2\]. Hence, option (A) is correct.
The oxidation state of ferrous chloride will not equal \[ + 3\]. Hence, the option (B) is incorrect.
The oxidation state of $Fe$ in \[FeC{l_2}\] is not equal to \[ + 4\]. Hence, the option (C) is incorrect.
By substituting the oxidation state of chloride in \[FeC{l_2}\], the oxidation state of iron will not get as \[ + 5\]. Hence, the option (D) is incorrect.

So, the correct answer is “Option A”.

Note:
As we know, the oxidation – reduction reaction is also known as redox reaction. This is a type of chemical reaction that undergoes the transfer of electrons between two species. During a chemical reaction, the oxidation state of an atom, molecule or ion may change. It may increase or decrease the oxidation number by losing or gaining the electrons.