Weeks of April 5, 2009 and April 12, 2010

This is a two-week laboratory experiment, the lab report sheets are due during the week of April 16, 2010

EXPERIMENT 21-116 The Chemistry of Some Common Inorganic Substances: Qualitative Analysis

The goal of this experiment is to devise a plan that will allow the identification each of 14 common inorganic substances listed in Table 1. There is no fixed experimental plan; no instruction will be given in this experiment. The idea is to learn as much as possible about the chemical and physical properties of the 14 substances, and come to laboratory prepared to carry out experiments designed to identify them.

0.1 Ba(NO₃)₂	0.1 M AgNO₃	0.5 M NH₃
0.1 M FeCl₃	0.3 M Na₂CO₃	0.1 M ZnSO₄
1.0 M LiOH	0.1 M Al(NO₃)₃	0.1 M CoCl₂
0.3 M KSCN	0.1 M CuSO₄	0.1 M KI
0.3 M H₂SO₄	0.1 M SrCl₂

It would be beneficial start with a chemistry textbook and research the chemical and physical properties that might be used to identify the materials, paying special attention to possible chemical reactions that might occur between pairs of the fourteen substances.

There is one important limitation on the experiment: no chemical reagents other than the fourteen which are issued may be used. Supplies listed in the materials sections on page 119 of the lab manual will be available for use, and perhaps additional equipment or supplies subject to availability in the Chemistry Department stockroom at Colgate, and the judgment of the laboratory instructor.

There is no "one" way or "correct" method to identify the fourteen solutions. There are many acceptable solutions, limited only by imagination and ingenuity. You will have 2 laboratory periods (8 hours) and only two laboratory periods to complete this assignment. If you need to change your lab section either this week or next week please see Dr. Chanatry as soon as possible.

Solutions. Each student will be issued 14 solutions which correspond to those listed above. Your job is to identify and label all 14 solutions by carrying out various chemical and physical manipulations. You will receive about 7-8 mL of each solution and this will be all that you will receive, so use your solutions wisely.

In your laboratory notebook, record the procedures and observations for each experiment you performed. For each of your solutions, describe at least one physical (if possible) and at least two chemical tests which help identify it. Your grade on this laboratory will be based on the number of correctly identified solutions, on the imagination and quality of your experimental methods, and on the clarity and logic used in justifying your assignments.

For each solution, indicate what chemical or physical tests were used for the identification, and write appropriate chemical equations as necessary. In one or two sentences, explain what experimental observations led you to your conclusions. Document your answers with appropriate references. An example is given below for a solution not among the fourteen you have been given. The example illustrates the type of information you might present in your report. You may think of additional types of information to include.

Original solution was observed to be light green in color. Aqueous Ni²⁺ solutions are green due to the formation of the hexaaquanickel(II) ion [Ni(H₂O)₆²⁺] (Brady & Humiston, General Chemistry, 4th Ed., p. 779).

When combined with solution #5 (previously identified as NaOH), a light green precipitate was formed. Aqueous Ni²⁺ forms an insoluble, light-green hydroxide (Radel and Navidi, Chemistry, 2nd Ed., p. 1024, Fig 21.37; Chemical Rubber Handbook, 63rd Ed.)

This identification was confirmed by reaction with solution #2 (previously identified as NH_3(aq)) as the blue-purple color, characteristic of the hexaaminenickel(II) dication, formed (Radel and Navidi, Chemistry, 2nd Ed., p. 1024, Fig 21.37).

The presence of the Cl^-_(aq) ion was confirmed by reaction with solution #11 (previously identified as a solution of AgNO₃). Silver chloride is quite insoluble in water (Radel and Navidi, Chemistry, 2nd Ed., p. 841), and when solution #1 (unknown) was mixed with #11 (AgNO₃), a white precipitate formed immediately.

You may use the Web, but I caution you to make sure that sources you use provide you with accurate information. You will also need to properly reference those sources. Please see the Chemistry 264 web page for links to suggested formats for citations of electronic sources.

An Improved Method for Students' Flame Tests in Qualitative Analysis, Bare, W.D., Bradley, T., and Pulliam, E., J. Chem. Educ., 1998, 75, 459.

Methods of Quantitative Inorganic Analyisis, K. Kodama, 1963, Cooley copy QD101.K76, 1963

Basic Inorganic Chemistry, Cotton & Wilkson, 1987, Cooley copy QD151.2 c 69, 1987

Internet: The links provided below are to get you started. You may use information found on the Internet, but you must cite the sources you used. As stated above, there is no guarantee that the informaion you find on the Internet is accurate. You should verify that all information is accurate before including it as a reference source.

General Chemistry On-Line: A very useful site (Fred Senese, Dept. of Chemistry, Frostburg State University).

Lab Report Sheets for Experiment 21-116: Acrobat Reader is required to read this file.