Question

Green edged flame test for `BO_(3)^(3-)` with alcohol and conc. `H_(2)SO_(4)` is generally carried out in a china dish. However, the test should be carried out in a test tube if one of the cation present in solution is
A. `Ba^(2+)`
B. `Cu^(2+)`
C. `Ca^(2+)`
D. `Zn^(2+)`

Answer 1

Green edged flame test for `BO_(3)^(3-)` should be carried out in a test tube when `Cu^(2+)` ions are also present in the mixture. This is because `Cu^(2+)` ions also give a green flame in flame test. When the test is carried out in a test tube the green edged flame is only due to the volatile `(C_(2)H_(5))_(3)BO_(3)` as `Cu^(2+)` ions are not volatile in solution.