Video: Solubilities of alkali metal ions
As described in video clip DIC4-05-100, the larger alkali metal ions form precipitates with large, low-charge anions. The standard test for the larger alkali metal cations is the hexanitritocobaltate(III) ion:3 K+(aq) + [Co(NO2)6]3-(aq) ® K3[Co(NO2)6](s)