Question

What is the role of chlorine in the following reaction? $Mg + C{l_2} \to MgC{l_2}$
(A) Oxidising agent
(B) Reducing agent
(C) Catalyst
(D) Provide inert medium

Answer 1

We know that the compounds undergo redox reaction where oxidation and reduction takes place simultaneously involving the loss or gain of one or more than one electron, losing or accepting/gaining of hydrogen atoms as well as oxygen atoms and the oxidation states also vary accordingly.

Complete answer: As we know that the redox reactions which involves both oxidation and reduction reactions simultaneously are very commonly found and we also know that oxidation state of the chemical species also changes in these types of reactions by losing or accepting one or more than one electrons.
In the given reaction, we can see that magnesium and chlorine are present in their native state, so their oxidation states are considered zero as elemental form possess no charge but when the product formation took place the oxidation states changed. Magnesium chloride now possess a $+ 2$ oxidation state for magnesium and $- 1$ oxidation state of chlorine which suggested that chlorine acts as an oxidising agent in the reaction where, chlorine itself got reduced and oxidised magnesium to form magnesium chloride adding an electropositive element in the product. Thus we can say oxidation and reduction both took place in the reaction.
Therefore, we can assume that chlorine plays a role of oxidising agent and magnesium plays a role of reducing agent in the following reaction.

Hence, the correct answer is option (A).

Note: Remember that when magnesium reacts with chlorine, it loses two electrons from its outermost valence shell and these electrons are shared by two chlorine atoms each getting one electron thereby making the stable compound which is magnesium chloride.