3. Sodium

1. Magnesium uranyl-acetate (Acetate of magnesium and uranyl, Kahane's reagent Blanchetière's reagent)

$Na^+$ $+$ $CH_3COO^-$ $+$ $Mg^{2+}$ $+$ $3UO_2^{2+}$ $\longrightarrow$ $\rm\small (CH_3COO)_9NaMg(UO_2)_3$ - yellow-greenish precipitate , fluorescent in U.V. - Interfere . Acids . The phosphate anion . Cations $Ba^{2+}, Sr^{2+}, Ag^+$

2. Potassium dihydrogendiantimonate

$2Na^+$ $+$ $H_2Sb_2O_7^{2-}$ $\longrightarrow$ $Na_2H_2Sb_2O_7$ - White precipitate - The reaction is promoted . by rubbing with a rod . by the addition of alcohol - Interfere . Acids . The ammonium cation . The cation $K^+$ in appreciable qty