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Abstract Two unknowns were attempted to be identified by a series of solubility tests, followed by a series of functional group tests. Derivatives of the compounds were to be formed to confirm the identity of the substances. The solid did not have a melting point, rather, it sublimed. The solid and liquid were tested for solubility in water, 5% NaOH, 5% NaHCO3, 5% HCL, and H2SO4. The liquid was found to have a boiling point of 184°C. The liquid was tested using the beilstein test for halogens, the ferric chloride test for phenols, 2,4-DNP for carbonyls, Br/CCl4 for multiple bonds, and the Tollens test for aldehydes. No derivative could be formed with the liquid because the sample evaporated. It was concluded that the liquid was benzaldehyde, which has a BP of 179°C. Introduction Qualitative analysis of unknown compounds is based on functional group chemistry. Several different classification tests can be performed on a substance to determine the functional groups that are present, or absent for that matter. For example, the Beilstein test, tests for halogens. A copper wire is heated and then coated with the sample and then heated again. If a green flame is present, this is a positive result. The green flame is the result of the production of a volatile copper halide (2). The most important tests that should be performed initially are the solubility tests. These tests give important information about the functional groups present. For example, compounds that contain 4 or less carbons, and contain oxygen, nitrogen, or sulfur are usually soluble in water (2). A flow chart on page 434 of the lab text outlines the procedure to follow for the solubility tests. Identity of unknown compound can be concluded by logical elimination of certain functional groups, and by using the results of each classification test to narrow the possibilities.
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