Is it possible to recognise sodium ions without using flame?

1 Answer
Jul 26, 2017

Yes, it is possible to test for sodium ions without using a flame.

Explanation:

The test is based on the formation of an insoluble sodium salt.

Put 1 small drop of conc. "H"_2"SO"_4H2SO4 in the cavity of a microscope slide.

Add 1 very small particle (max. "1 mm"^31 mm3) of "Bi"("NO"_3)_3Bi(NO3)3 to the drop.

Stir briskly for 1 to 2 min with a glass rod ["Bi"("NO"_3)_3Bi(NO3)3 dissolves very slowly].

When the solution is saturated, the acidic drop becomes white and stiff and swells visibly.

Add 1 drop of deionized water and stir vigorously.

When the white salt is dissolved the solution should be colourless or perhaps opalescent.

Add 1 drop of 2 mol/L "HNO"_3HNO3.

The reagent is now ready to be used.

Test for "Na"^"+"Na+

Add 1 drop of the reagent solution to a previously dried test drop on an object slide.

Observe the reaction products under the microscope at a magnification of about 100X.

Usually, "Na"^"+"Na+ quickly forms needles of the insoluble salt, "3Na"_2"SO"_4·"2Bi"_2("SO"_4)_3·2"H"_2"O"3Na2SO42Bi2(SO4)32H2O.