22. Antimony

1. $H_2S$

$2Sb^{3+}$ $+$ $3S^{2-}$ $+$ $12H^+$ $\longrightarrow$ $Sb_2S_3$ - Orange precipitate - Can darken by boiling - Soluble in $(NH_4)_2S$ - Soluble in $KOH$ - Soluble in fuming $HCl$ - Previous cases: reprecipitation by $HCl$ or diluted $H_2SO_4$ - Insoluble in $(NH_4)_2CO_3$ - Insoluble in $NH_3$

2. $KOH$

$Sb^{3+}+3OH^- \longrightarrow Sb(OH)_3$ - White precipitate - Soluble in an excess of reagent: $Sb(OH)_3$ $+$ $OH^-$ $\longrightarrow$ $Sb(OH)_4^-$ - Tetrahydroxoantimonate(III)

3. $NH_3$

$Sb^{3+}$ $+$ $3OH^-$ $\longrightarrow$ $Sb(OH)_3$ - White precipitate - Insoluble in an excess of reagent:

4. Hydrolysis

$SbCl^{2+}$ $+$ $H_2O$ $\longrightarrow$ $2H^+$ $+$ $SbOCl$ - Antimonyl chloride - "Oxychloride" - Soluble in $HCl$ - Soluble in tartaric acid $(\neq BiOCl)$

5. Displacement

$Fe$ $+$ $Sb^{3+}$ $\longrightarrow$ $Fe^{3+}$ $+$ $Sb$ - Black deposit on iron - There is also production of $SbH_3$ (toxic gas)

6. Hydrolysis

$SbCl^{2+}$ $+$ $H_2O$ $\longrightarrow$ $2H^+$ $+$ $SbOCl$ - Antimonyl chloride - "Oxychloride" - Soluble in $HCl$ - Soluble in tartaric acid $(\neq BiOCl)$

7. Rhodamine B

- In the presence of $HCl$ and little $KNO_2$ turn from orange to purple - Operate on porcelain plate in the presence of witnesses!