Question

When \[Mn{O_2}\] dissolves in \[HCl\] to form:
A) \[M{n^{4 + }}\] ion and \[C{l_2}\]
B) \[M{n^{2 + }}\] ion and \[C{l_2}\]
C) \[{\left[ {MnC{l_4}} \right]^{2 - }}\] and \[C{l_2}\]
D) Only \[{\left[ {MnC{l_4}} \right]^{2 - }}\]

Answer 1

Hint: We have to know that the oxidation-reduction (redox) processes are an extremely important aspect of sample dissolution. The analyte may be present in a sample in several different chemical forms or oxidation states. Reduction reaction is a chemical reaction in which oxygen is removed from or hydrogen is added to an element, molecule or compound.

Complete answer:
As we know, when concentrated hydrochloric acid ( \[HCl\]) reacts with manganese dioxide, chlorine gas, manganese (II) chloride and water are liberated. So chlorine gas evolves when \[HCl\] acid is added to manganese dioxide.
$Mn{O_2} + 4HCl \to MnC{l_2} + 2{H_2}O + C{l_2}$
A redox reaction redistributes electrons among the atoms, molecules, or ions in the reaction. In some redox reactions, electrons actually are transferred from one reacting species to another. In other redox reactions, electrons are not transferred completely from one reacting species to another; the electron density about one atom decreases, while it increases about another atom. Manganese dioxide 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. Naturally occurring manganese dioxide contains impurities and a considerable amount of manganese (III) oxide. Only a limited number of deposits contain the gamma modification in purity sufficient for the battery industry.

Note:
We need to know that hydrochloric acid is the water-based, or aqueous, solution of hydrogen chloride gas. It is also the main component of gastric acid, an acid produced naturally in the human stomach to help digest food. Hydrochloric acid is also used in the production of batteries, photoflash bulbs and fireworks. It's even used to process sugar and make gelatin.