Question

Why is the test tube inclined in ring test.?​

Answer 1

The brown ring test is performed byputting iron(II) sulfate to a solution that contains nitrate ions. After that, slowly and carefully add concentrated sulphuric acid

Answer 2

The brown ring test is a test for the presence of nitrate ions (NO3-) in solution. The test is very simple. Here is the procedure:

Put a sample of your test solution (3 mL) into a test tube and acidify it with 3 M H2SO4 (1 mL).

Add a 1 mL of freshly made FeSO4 and mix well.

Now, slowly, carefully, add concentrated H2SO4 down the side of the test tube (tilt the tube).

The sulfuric acid is very dense and it will pass through your test solution and go to the bottom of your test tube. At the interface between the concentrated H2SO4 and the test solution, a brown ring will form if nitrate is present in the test solution.

The combination of Fe2+ and H2SO4 converts the nitrate ion into NO. The NO then complexes with the Fe2+ to make FeNO2+ which is a brown-green complex ion. Since this reaction occurs at the interface between the test solution and the concentrated H2SO4, the FeNO2+ complex ion makes what appears to be a brown ring at the interface.

Now, the complex itself, though often written as FeNO2+ is actually Fe(H2O)5NO2+. It is an iron II ion in the center of an octahedral complex with five water molecules and one NO molecule surrounding it. Since sulfate is present, the compound made would be Fe(H2O)5NOSO4, or pentaaquanitrosyliron(II) sulfate.

Hope it helps ~♥~~♥~~♥~