Add NH4OH until the solution is basic to litmus.
Add KH2PO4 solution drop by drop. A white precipitate
of MgNH4PO4 confirms the presence of the Mg2+
Evaporate to dryness. Add dilute HNO3, evaporate
Once the evaporating dish is cool, add 2 mL of distilled water and
divide evenly into 2 parts.
Add 2 mL of magnesium uranyl acetate. Cool the solution. Scrap
the walls of the test tube to help crystallization.
Very pale yellow crystals confirms the presence of Na1+.
Add 2 mL of HCl and 2 mL of sodium cobaltinitrite solution.
Warm, then cool quickly.
Scrap the walls to help precipitation. A pale yellowish-brown
precipitate confirms the presence of the K1+ ion.