Rhodium test:
Take a liquid sample, add sodium acetate to saturation (buffer). Add carefully solid sodium nitrite, NaNO2 or 60% solution, until end of brown fumes evolvement. Yellow/green color should develop. Heat over a plate or in a hot air flow for an hour. Add carefully ammonium hydroxide solution. A yellow/brown precipitate should form. Formula: (NH4)3Rh(NO2)6, ammonium hexanitro rhodate.
Take a liquid sample, add sodium acetate to saturation (buffer). Add carefully solid sodium nitrite, NaNO2 or 60% solution, until end of brown fumes evolvement. Yellow/green color should develop. Heat over a plate or in a hot air flow for an hour. Add carefully ammonium hydroxide solution. A yellow/brown precipitate should form. Formula: (NH4)3Rh(NO2)6, ammonium hexanitro rhodate.
