Question

Name a substance that oxidizes concentrated $HCl$ to chlorine.

Answer 1

An oxidizing agent is a reactant that removes electrons from other reactants during a redox reaction. The oxidizing agent typically takes these electrons for itself, thus gaining electrons and being reduced. An oxidizing agent is thus an electron acceptor.

Complete step by step answer:
We require a substance that oxidizes $HCl$ to chlorine. So the required substance should be an oxidizing agent.
The substance will be potassium permanganate.
The balanced chemical reaction of potassium permanganate and $HCl$ is as follows:
$2KMn{{O}_{4}}\,+\,16HCl\,\to \,2MnC{{l}_{2}}\,+\,2KCl\,+\,8{{H}_{2}}O\,+\,5C{{l}_{2}}$

Additional information:
Another substance that oxidizes $HCl$ to chlorine is manganese dioxide. The balanced reaction of manganese dioxide and $HCl$ is as follows:
$Mn{{O}_{2}}\,+\,4HCl\,\to \,MnC{{l}_{2}}\,+\,2{{H}_{2}}O\,+\,C{{l}_{2}}$
Potassium permanganate is an inorganic compound with the chemical formula KMnO4 and composed of K+ and $Mn{{O}^{-}}$. It is a purplish-black crystalline solid that dissolves in water to give intensely pink or purple solutions. [Citation needed]
Manganese (IV) oxide is the inorganic compound with the formula $Mn{{O}_{2}}$. This blackish or brown solid occurs naturally as the mineral pyrolusite, which is the main ore of manganese and a component of manganese nodules. The principal use for $Mn{{O}_{2}}$ is for dry-cell batteries, such as the alkaline battery and the zinc-carbon battery.$Mn{{O}_{2}}$Is also used as a pigment and as a precursor to other manganese compounds, such as $KMn{{O}_{4}}$
It is used as a reagent in organic synthesis, for example, for the oxidation of allylic alcohols. $Mn{{O}_{2}}$ in the $\alpha$ polymorph can incorporate a variety of atoms (as well as water molecules) in the "tunnels" or "channels" between the manganese oxide octahedra. There is considerable interest in $\alpha$ -$Mn{{O}_{2}}$as a possible cathode for lithium ion batteries.

Note: Potassium permanganate is widely used in the chemical industry and laboratories as a strong oxidizing agent, and also as a medication for dermatitis, for cleaning wounds, and general disinfection. It is on the WHO Model List of Essential Medicines, the safest and most effective medicines needed in a health system.