Question

Give the test that is used to detect borate radicals is qualitative analysis.

Answer 1

1. Borax when heated with ethyl alcohol and concentrated H₂SO₄, produces volatile vapours of triethyl borate, which burns with green edged flame.
   a. \[\ce{\underset{\text{Borax}}{Na2B4O7} + \underset{\text{(conc.)}}{H2SO4} + 5H2O->[\Delta]\underset{\text{Sodium sulphate}}{Na2SO4} + \underset{\text{Orthoboric acid}}{4H3BO3}}\]
   b. \[\ce{\underset{\text{Orthoboric acid}}{H3BO3} + \underset{\text{Ethyl alcohol}}{3C2H5OH}->\underset{\text{Triethyl borate}}{B(OC2H5)3} + 3H2O}\]
2. The above reaction is used as a test for the detection and removal of borate radical \[\ce{(BO^3-_3)}\] in qualitative analysis.