Part 1: INTRODUCTION
In this experiment, students will continue the qualitative analysis of unknown solutions and the unknown crystals. Today the Q-3 ion scheme, which describes the analysis of Co2+, Fe3+, Ni2+, Al3+, and Zn2+ will be performed. As before, this analysis will first be carried out on a known solution that the students will prepare. Also, an unknown solution from the professor as well as the green crystals will be tested. Prior to lab, be sure to have specified number of copies of the Q-3 skeleton flow chart.
The objective of this experiment is to continue learning about qualitative analysis and how to identify the ions listed above in an unknown via the Q-3 qual scheme.
On this website, there will only be the positive results of the known solutions. Therefore, you should use this page only as a guidance to make connections between what you are observing and what is actually happening in the test tube. For detailed steps, follow your lab manual.
Part 2: Positive Results
2.1: Iron / Fe3+
Confirmation of the presence of iron: Formation of a deep red solution of FeSCN2+(aq) is a definitive test for iron. Read the notes on the lab manual regarding the test for iron.
2.2: Cobalt / Co2+
Confirmation of the presence of cobalt: The formation of a blue solutioncontaining Co(SCN)4 2-(aq) is a positive test for cobalt. Read through your manual for more specific procedure.
2.3: Nickel / Ni2+
Confirmation of the presence of nickel: Formation of a rose-red precipitateproves the presence of nickel. Read through your manual for more specific instruction.
2.4: Aluminum / Al3+
Confirmation of the presence of aluminum: To test for aluminum, the solution needs to be slightly acidic. If Al3+ is present, the solution will turn blue. Follow the instructions in the lab manual.
2.5: Zinc / Zn2+
Confirmation of the presence of zinc: If zinc is present, you will obtain a light green (green-blue) precipitate of K2Zn3[Fe(CN)6]2(s). Read through the notes in the lab manual to get a definitive result.