Chemical Forums

Chemistry Forums for Students => Analytical Chemistry Forum => Topic started by: uoste211 on November 25, 2018, 07:48:53 PM

Title: Thermite: Manganese as an Oxidizer
Post by: uoste211 on November 25, 2018, 07:48:53 PM

Hello everyone, I've been trying to find a way to obtain elemental boron, and the idea of thermite interested me. Because who doesn't enjoy fire?

For my boron source, I plan to use boric oxide (B2O3). But have been toying with the oxidizer. I know I could easily just use aluminum powder or magnesium powder, but I had some manganese powder laying around and it made me wonder if it could be used in the thermite reaction. Manganese as an oxide (Mn2O3) is a great reducer for thermites, but as the metal? I would love to hear what anyone thinks about this topic.

Thanks

Title: Re: Thermite: Manganese as an Oxidizer
Post by: Enthalpy on November 26, 2018, 12:32:36 PM

Welcome, uoste211!

Beware many boron compounds are seriously toxic, and what you plan will release dust in the air.

Manganese isn't an efficient reducer. In a first, simplified analysis, you can compare the heat of formation of the oxides per atom of oxygen:
kJ/mol O
-274.7 (*3) Fe₂O₃
-279.6 (*4) Fe₃O₄
-385.2 (*1) MnO, provided this oxide forms. The others are worse.
-424.5 (*3) B₂O₃
-558.6 (*3) Al₂O₃
-601.6 (*1) MgO
I expect no reaction at all.

You need a table of the heat (or enthalpy) of formation of the compounds. There are some on the Web.