Preliminary instructions
• Always clean each and every instrument you use as carefully as possible (especially for ion detection this is
a requirement). If you know/imagine how small an atom is you may imagine which amount of residue of
another substance leads to false positives.
• Also if you got a salt, take a fraction of it into another (clean) test tube and solve it in H2O (clean distilled
water!). This is your basic sample now.
• For each test take a small (!) probe of the basic sample into another test tube and make the respective test.
Afterwards clean it. Take another bit and perform the next test. Never try to perform multiple tests on one
and the same probe.
No joke: If you are allergic to certain substances or if you are color blind, please tell the supervisor or the
professor. The latter one is hindering the first one may be dangerous.
Proposal on the order of tests for ion detection
See the tables below for any detailed instructions. Follow the steps and always consider that, if you have one
compound to detect, it will only contain one anion and one cation. Everything else would be a mix. So you can
stop testing when you are sure you detected the correct ions. Also note, that the supervisor does not always
work properly as well. My mixed probe was „to well“mixed and contained something else than listed. In such
case ask for a new and clean probe instead of being pissed off because of their mistake!!!
1. First of all take a look on the salt or solution. Does it have a color? The color may already give a hint what
ions it contains. See the following overview:
Color
Probably contains:
blue
Copper ions (Cu2+)
green
Nickel (Ni2+) or Chromium (Cr3+) ions
brown
Bi- (Fe2+) or trivalent (Fe3+) Iron ions
But note, that this is not a final result. It just gives a hint and makes life easier.
2. Perform a flame test. Possible results can be taken from the table for cations.
Flame test instructions:
•
take a magnesia stick and anneal it using a burner, until the flame is colorless.
•
if you got a solid compound j