Identification of CompoundsIdentifying Compounds in Solution
Knowing the properties of acids and bases makes it possible to identify acidic and basic solutions using very simple tests. A knowledge of solubility rules coupled with the observation of precipitation reactions makes it possible to identify other solutions in addition to acids and bases. One variant of this process is called qualitative analysis and involves testing unknown solutions with known chemical reagents. Another variant (used in this lesson) involves the interactions among a small set of known but unlabeled solutions (along with acid/base tests) to determine which is which.
In this section we get into what I consider to be the most interesting part of the lesson, and that is using reactions to identify chemicals. You will do most of this yourself in the lab by performing what we call the "five solutions experiment." I think it's fun because it is a bit like detective work.
You will try to match the behavior of five chemical solutions with the formulas of the chemicals that are dissolved in those solutions. You will have to look at the formulas of those chemicals and infer what kinds of chemical reactions and chemical properties those chemicals will have. You will also have to observe the reactions of the solutions themselves and match them with the predictions you make based on the formulas.
To help you with that, some useful information is reviewed on the Useful Information page (and in Examples 29 and 30 in your workbook).
Then check out the Experiment Preview with an example of a similar problem worked through.
Then, before you actually perform your experiments, do the six-solutions practice problem and have the instructor check it. If you can do that, then you should be able to analyze the data that you collect in the experiment. Ask the instructor for your combination of formulas and bottle numbers. Each person will have their own combination, although you may want to consult with one another. Staple or tape your slip to your report when you turn it in.
Your lab report for this experiment need not be written in the usual format. Instead, if you wish, simply write in the "purpose" at the beginning of the experiment and turn in the "report sheets" from your workbook. Under "Results" it will simplify the grading process for me if you list the solutions and their identities in the order in which you figure them out.
When you have done that and have reviewed and understand the objectives, you are done with this lesson. Good luck and I hope you have fun doing this experiment.
Distance Learning questions
Clackamas Community College