Synthesis and Characterization of a Layered Manganese Oxide: Materials Chemistry for the Inorganic or Instrumental Methods Lab

A three-week laboratory project involving synthesis and characterization of a layered manganese oxide provides an excellent vehicle for teaching important concepts of inorganic chemistry and instrumental methods related to non-molecular systems. Na–birnessite is an easily prepared manganese oxide with a 7 Å interlayer spacing and Na+ cations and water in the interstitial region. The material is readily characterized by powder X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, elemental analysis, and Mn oxidation state determination. It also undergoes facile ion exchange with Mg2+ to yield Mg–buserite, an analogous manganese oxide with a 9.6 Å interlayer spacing. Diffraction patterns and physical morphology can be related to the layered structure of the material. A thorough compositional analysis can also be done, which includes determination of mixed valency and interstitial hydration.