Manganese (Mn) - Properties, Applications

Topics Covered

Introduction
Chemical Properties
Physical Properties
Mechanical Properties
Thermal Properties
Applications

Introduction

Manganese is a pinkish-gray, chemically active element with Mn as its symbol. It belongs to group 7, periodic number 4 of the periodic table. Its atomic number is 25.

Manganese is obtained from the minerals pyrolusite and rhodochriste. It is a hard and very brittle metal that reacts with water and dissolves in dilute acids. The metal tends to rust like iron when exposed to water.

Leading producers of manganese are Australia, Brazil, South Africa, Gabon and India.

Chemical Properties

The chemical properties of manganese are provided in the table below.

Chemical Data
CAS number 7439-96-5
Thermal neutron cross section 12.6 barns/atom
Electrode potential -1.05 V
Ionic radius 0.460 Å
Electronegativity 1.55
X-ray absorption edge 1.896 Å
Electrochemical equivalent 0.684 g/A/h

Physical Properties

The following table discusses the physical properties of manganese.

Properties Metric Imperial
Density 7.44 g/cm3 0.269 lb/in3
Melting point 1247 °C 2277°F
Boiling point 2061 °C 3742°F

Mechanical Properties

The mechanical properties of manganese are tabulated below.

Properties Metric Imperial
Tensile strength 496 MPa 71900 psi
Yield strength 241 MPa 35000 psi
Poisson’s ratio 0.35 0.35
Modulus of elasticity 159 GPa 23100 ksi
Shear modulus 76.4 GPa 11100 ksi
Hardness, Brinell 460 460
Hardness, Vickers 500 500
Hardness, Rockwell A 75 75
Hardness, Rockwell C 48 48

Thermal Properties

The thermal properties of manganese are tabulated below.

Properties Metric Imperial
Thermal expansion co-efficient (@20-100°C/68-212°F) 22.8 µm/m°C 12.7 µin/in°F
Thermal conductivity 1.64 W/mK 11.4 BTU in/hr.ft².°F

Applications

Almost 90% of the manganese produced annually is used in the production of steel.

The following are the application areas of manganese:

  • To depolarize dry cells
  • As an alloying component in a wide variety of steel and other alloys
  • To provide glass an amethyst color and to provide color to amethyst gemstones

Manganese can be formed into many useful compounds. Some are listed below with their specific application areas:

  • Potassium permanganate - used as a disinfectant
  • Manganese oxide - in fertilizers and ceramics
  • Manganese carbonate – as a starting material for making other manganese compounds
  • Manganese dioxide - as a catalyst.

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