Beilstein Test for Halogens...Procedure questions?

Question

Procedure:

Obtain a piece of copper wire. Note the color of the wire and record your observation. Make a loop at one end of the wire and eat it to red hot. Allow it to cool and note the change in color of the wire.

Dip the heated copper wire in METHYLENE CHLORIDE Solution. Heat the loop and note the color imparted to the flame.

Reapeat the procedure using IODOFORM.

Results:
Both copper wires produced a green flame.

So, here are my questions:
1. What is the role of the heated copper wire in the reaction?
2. Is the beilstein test a conclusive test for a particular halogen? Why/not?
3. Give the principle involved in this test.

P.S. Thank you for those people who wouldn't flame this....

Answer 1

You got the same colour in both tests, so the test detects halogen but doesn't tell you which one.

Flame colour is a property of the element. The element you have in common is copper.

So, principle is, copper reacts to give copper halide, which is volatile enough to give the characteristic Cu green to the flame. If there are other things that would give volatile Cu compounds (there may be; I don't know), they will also give positive Beilstein tests.

Answer 2

I love this little test, I remember it from my first job and I got 3/4 when all the managers got none, I thought it was easy then but I understand why people get confused. Thanks for posting it I can copy it to all my freinds for a giggle.