Naked Science Forum

Non Life Sciences => Chemistry => Topic started by: Seany on 18/04/2011 11:13:53

Title: Test for Barium Hydroxide?
Post by: Seany on 18/04/2011 11:13:53

Here is the question..

A solution, giving an apple-green colour to a flame, was suspected to be aqueous barium hydroxide.
Describe two simple tests to confirm this conclusion, giving the result of each test.

Now, I've only been taught that to test for Barium ions you do a flame test, which gives an apple-green colour!
Do I do litmus to test for alkalinity?

Title: Test for Barium Hydroxide?
Post by: Seany on 18/04/2011 11:37:04

Also.. The manufacture and use of 1,1,1-trichloroethane is now restricted because of its adverse effects on the ozone layer. However, the corresponding fluoro-compound 1,1,1-trifluoroethane does not cause environmental problems in the ozone layer. Explain why only the chloro-compound has these adverse effects.

Title: Test for Barium Hydroxide?
Post by: lightarrow on 18/04/2011 15:36:44

Quote from: Seany on 18/04/2011 11:13:53

Here is the question..

A solution, giving an apple-green colour to a flame, was suspected to be aqueous barium hydroxide.
Describe two simple tests to confirm this conclusion, giving the result of each test.

Now, I've only been taught that to test for Barium ions you do a flame test, which gives an apple-green colour!
Do I do litmus to test for alkalinity?

sulphate and/or carbonate.

Title: Test for Barium Hydroxide?
Post by: Seany on 18/04/2011 15:52:52

Eh?

Title: Test for Barium Hydroxide?
Post by: Bored chemist on 18/04/2011 19:15:18

A fair few things will give a ppt with carbonate.
Even the ppt with sulphate isn't specific.

Title: Test for Barium Hydroxide?
Post by: lightarrow on 18/04/2011 19:51:54

first test with CrO₄^2-; second with SO₄^2-. Ba precipitates in both, Ca and Sr only in the second.
In case the OP is sure there is just one metal cation in solution, the green colour could be Ba, Cu or Tl. Then the test with sulphate is enough because copper and thallium sulphates are soluble.

Title: Test for Barium Hydroxide?
Post by: Bored chemist on 18/04/2011 21:53:23

"Do I do litmus to test for alkalinity?"
It would be a good start.
Another thing you might try is blowing through it, but can you explain why that would help?


For the other question, what do you know about the mechanism of ozone destruction?