Inorganic Pigment Synthesis Lab Report

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The main purpose of this experiment was to synthesize a series of inorganic pigments, qualitatively observe their macroscopic and microscopic properties and perform a series of qualitative micro-chemical spot tests on them. The other purpose was to design a qualitative analysis experiment for the purpose of identifying an unknown inorganic pigment. In the first week of this experiment, barium white, zinc yellow and chromium oxide green were synthesized using macroscopic inorganic pigment reactions. The final yield of chromium oxide green was found to be 0.2001 g with a yield of 11.50 %. Prussian blue was synthesized using microscopic inorganic pigment reactions. In the second week of the experiment the micro-chemical…show more content…
Only the synthesis of chromium oxide green, one of the four that occurred will be shown here. Chromium oxide green was synthesized using 3.0000 g of bright orange sodium dichromate (Mallinckrodt) and 1.0000 g of lime­yellow sulfur (BDH). Both solids were grinded using a mortar and pestle until the powder was very fine and well mixed. Then the ground mixture was transferred into a porcelain dish using a weigh paper. The Bunsen burner was then set up with a ring stand and wire triangle in the hood. The porcelain dish was placed in a wire triangle and was adjusted about 1.5 inches above the top of the burner. First gas with red bubbles appeared, which was observed to darken while reacting intensely with the fire. This process continued until gas evolution ceased. The crucible was then left to cool down. After cooling, the product gradually went from black to dark green; it was then transferred into a second clean mortar and ground with a pestle until it formed a fine powder. The fine powder was transferred into a 250 mL beaker (water was used to transfer it from the mortar), where 25 mL of water was added (while stirring vigorously) to remove the unreacted starting material. The remaining green solid was filtered by vacuum filtration using a Buchner funnel. The filtrate was then rinsed with clear acetone which allowed the pigment to dry. The dry pigment had a dusty green appearance to
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