Paint Pigment Essay

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The History of Paint Pigments

Chem 111-404
April 24, 2013

This report expresses five different pigments that were formed during chemical reactions. Three out of the total five reactions went through a metathesis, or double-replacment reaction. A metathesis reaction can be defined as “a chemical reaction in which an element or radical in one compound exchanges places with another element or radical in another compound.” (Webster). The other two pigments underwent a neutralization reaction, which is “A reaction between an acid and a base that yields a salt and water.” (Webster). In both types of reaction two substances are being combined to form a new solution. The metathesis reaction produces a solution and a
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The first half was filtered and stored for the completion of the experiment, while the other half was stored for a week, unfiltered. The next week the unfiltered solution in beaker was filtered and set aside for another week.
The fifth, and final pigment, was Prussian blue. One milliliter of 0.5 M iron (III) chloride was measured into a test tube. Then, 0.25 M solution of potassium ferrocyanide was mixed in. They were then filtered, and left to dry. The next week there were four paint binding options: egg tempura, casein, acrylic, and water color or gum arabic. This experiment used watercolor. The first step was to grind the pigment with water to make a stiff paste. Then, gum Arabic was added in a 1:1 ratio.
The data produced from the experiment demonstrates that when two solutions are mixed, they undergo a reaction that produces a pigmented or colored precipitate and also a liquid. The precipitate produced then can be fashioned into paint. In the first pigment, chrome yellow was produced. The yellow sodium chromate combined with the clear zinc sulfate created an orange liquid and a yellow precipitate. This is a metathesis reaction that causes the solution to be neutralized. The addition of sodium hydroxide causes the solution to become more basic. After the solution was filtered it created a yellow solid, and when the precipitate was crushed up and gum Arabic was it created a yellow
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