Manganese: the metal that served in the army

Manganese reactions, properties and areas of application

In­tro­duc­tion

Man­ganese is a sil­very-white met­al that grad­u­al­ly dulls in air. Its melt­ing point is 1246°C (2275°F). It is frag­ile enough to break with a ham­mer.

Man­ganese is the 12th most com­mon chem­i­cal el­e­ment on Earth. It is most of­ten ob­tained from an ore known as py­ro­lusite (man­ganese diox­ide).

Dis­cov­ery his­to­ry

Man­ganese(IV) ox­ide has been known to hu­mans since time im­memo­ri­al. The cave draw­ings in Las­caux Cave (France), which are more than 10,000 years old, con­tain man­ganese in their com­po­si­tion.

Man­ganese com­pounds were used by glass blow­ers to bleach glass, and 18th-cen­tu­ry chemists used man­ganese diox­ide to pro­duce chlo­rine. Man­ganese was ob­tained as a sep­a­rate el­e­ment by Jo­hann Gann in 1774.

Chem­i­cal prop­er­ties

Man­ganese re­acts with oxy­gen to form a durable ox­ide film of man­ganese diox­ide. The re­ac­tion speeds up if heat­ed.

Mn + O₂ = MnO₂

Man­ganese ac­tive­ly dis­solves in acids, such as hy­drochlo­ric acid.

Mn + 2HCl = Mn­Cl₂ + H₂

When man­ganese diox­ide is fused with potas­si­um hy­drox­ide, green potas­si­um man­ganate is formed.

2M­nO₂ + 4KOH + O₂ = 2K₂M­nO₄ + 2H₂O

Vi­o­let potas­si­um per­man­ganate can be ob­tained via re­ac­tions be­tween acids (such as hy­drochlo­ric acid) and potas­si­um per­man­ganate.

K₂M­nO₄ + 4HCl = 2KM­nO₄ + MnO₂ + 2H₂O + 4KCl

Potas­si­um per­man­ganate is a strong ox­i­diz­ing agent. It can ox­i­dize glu­cose in an al­ka­line so­lu­tion, turn­ing first green (man­ganate form), then yel­low (fine man­ganese diox­ide), and ul­ti­mate­ly col­or­less (di­va­lent man­ganese ions form).

5C₆H₁₂O₆ + 24KM­nO₄ + 36H₂­SO₄ → 30­CO₂ + 24Mn­SO₄ + 12K₂­SO₄ + 66H₂O

Con­cen­trat­ed sul­fu­ric acid and potas­si­um per­man­ganate form green man­ganese ox­ide (VII), a strong ox­i­diz­ing agent. When brought into con­tact with al­co­hol, it ig­nites and ex­plodes.

C₂H₅OH + 2M­n₂O₇ = 4M­nO₂ + 2CO₂ + 3H₂O

Ap­pli­ca­tion

Man­ganese diox­ide is used to make al­ka­line and zinc-car­bon bat­ter­ies. An al­loy of bis­muth and man­ganese, bis­man­ol, has been used to make mag­nets. Adding man­ganese in­creas­es steel’s strength. An al­loy known as man­gal­loy was used to make mil­i­tary hel­mets due to its im­pact re­sis­tance and dura­bil­i­ty. Potas­si­um per­man­ganate is used in medicine to treat wounds, der­mati­tis, and fun­gal in­fec­tions.