 | ||
Make potassium precipitation sodium cobaltinitrite analytical chemistry lu le laboratory
Sodium cobaltinitrite is a coordination compound with the formula Na3Co(NO2)6. The anion of this yellow-coloured salt consists of a cobalt(III) center N-bonded to six nitrito ligands. It is a reagent for the qualitative test for potassium and ammonium ions.
Contents
Synthesis and reactions
The compound is prepared by oxidation of cobalt(II) salts in the presence of sodium nitrite:
4 [Co(H2O)6](NO3)2 + O2 + 24 NaNO2 → 4 Na3[Co(NO2)6] + 8 NaNO3 + 4 NaOH + 22 H2OApplication for analysis of potassium
Although the sodium cobaltinitrite is soluble in water, it forms the basis of a quantitative determination of potassium, thallium, and ammonium ions. Under the recommended reaction conditions the insoluble double salt, K2Na[Co(NO2)6]·H2O is precipitated and weighed. In geochemical analysis, sodium cobaltinitrite is used to distinguish alkali feldspars from plagioclase feldspars in thin section.
References
Sodium cobaltinitrite Wikipedia(Text) CC BY-SA