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A ll paints contain pigment, which provides color, and a binder (or medium), which suspends the pigments and binds them to the surface of the object to be painted. Two paint pigments, malachite and verdigris, are synthesized in this general chemistry laboratory experiment and then a tempera paint is made using malachite. While introducing the students to the composition of artists' paints, performing this experiment exposes students to chemical concepts such as stoichiometry (excess reactants and yields), solubility, precipitation, and properties of emulsions.Copper sulfate is the starting material for the one-step synthesis of malachite and the three-step synthesis of verdigris. Both syntheses can be done with a magnetic stir plate, standard glassware, and chemicals purchased from hardware stores and supermarkets. The products are dried and weighed to determine percent yields. Malachite pigment is combined with egg yolk binder to make tempera paint. A version of the student write-up for this experiment can be found in a laboratory manual that contains standard first-year general chemistry experiments, all of which can be done with household chemicals. 1 The experiment was tested by students enrolled in a general chemistry course. Knowing they would be required to finish both syntheses in one lab period was a strong motivation for students to read the experiment before coming to class to devise timesaving strategies. Results obtained from the class include time required to finish both syntheses, yields of both pigments, as well as the ideas used by students to make best use of their time.This experiment can also be used to explore green chemistry. Among the principles to classify a reaction as "green" are the use of nonhazardous starting materials, their maximum incorporation into products, use of ambient temperature for energy efficiency, and production of nontoxic products. The malachite dx.

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Liquid carboxylic acids (or primary amines) with limited solubility in water are dissolved by addition of aqueous sodium hydroxide (or hydrochloric acid) on the stage of an overhead projector using simple glassware and very small quantities of chemicals. This effective and colorful demonstration can be used to accompany discussions of the properties of carboxylic acids and amines in general chemistry as well as organic chemistry.