Chromium is highly insoluble in water. Chromium can only be in solution at a very low pH below 3.5. In this exercise we will generate Eh-pH diagrams to study stable and  soluble phases. Cr(VI) is much more toxic and mobile than Cr(III). So, speciation of chromium is very important. Hexavalent chromium exists in alkaline, strongly [Continue]

In this article we are going to investigate the Manganese solubility in natural water with the help of various Eh-pH diagrams. We will also investigate the effect of bicarbonate (alkalinity) and sulfate on Manganese solubility. At the end we will compare the solubility of manganese against iron solubility. Background: In natural surface and [Continue]

Alabandite is a sulfide mineral often found in epithermal sulfide vein deposits. The name of the mineral is derived from its supposed discovery locality at Alabanda, Aïdin, Turkey. Chemical Formula:     MnS Composition:     Molecular Weight = 87.00 gm General physical properties and color photograph of Alabandite can be found at [Continue]

It is wonderful what you can really do with Geochemist’s workbench. In this exercise, I am going to use the known concentrations of sea water and use Geochemist’s workbech to perform a little exercise. Geochemist workbench has different modules. In this particular excercise, I am going to use the SpecE8 module. This module is similar [Continue]

If you hate doing mole calculations by hand, check out this PHREEQC tip. Good thing about the free software by USGS is that you can input the variables as mg/L (or other units) and it will first speciate the solutions to give you the molality and moles for each component. Lets just use one example [Continue]