Formal Lab Report Synthesis

A small amount of the unknown (approximately the tip of the spatula was used for all the pigments) was added into each clean dry test tube. For the first test 1 mL of 3 M of HNO3 was added. As soon as the acid came into with the solid, the pigment was observed to dissolve while also turning the solution into a pale clear colour. The same amount was used for the HCl reagent. As soon as the acid touched the pigment it yielded in a clear solution (solid dissolved after a few shakes). When the KI was added, the solution turned a pale yellow with white solid precipitate clumping together at the bottom of the test tube. See Table 2 for observations. The unknown had heat administered to it as well, in order to solidify the identity of the unknown;
In the formation of barium white, the reaction involved was a double displacement reaction in which sodium in sodium sulfate being more reactive, was replaced by barium from barium chloride and was able to form barium sulfate, a white solid pigment and sodium chloride 2. As barium sulfate is insoluble in water it was relatively easy to observe and interpret what was happening as the chemicals mixed 2. The formation of zinc yellow also involved a double displacement reaction 3. The addition of zinc sulfate to potassium chromate formed a yellow coloured solution and when base was added, the solution turned into a bright yellow colour. This was difficult to observe as the colour change was very subtle, however, interpretation was manageable as pH paper was used to find when the addition of base should be stopped. Chromium oxide green was synthesized from the reaction between potassium dichromate and sulfur. The reaction involved heat thus, sulfur dioxide gas was released and colour change was observed from bright red to black. The final inorganic pigment was dark green. Due to the colour change it was easy to observe and interpret what was happening as the reactions progressed. The formation of Prussian blue used a microscopic reaction, that is the reactants were mixed together and their chemical reaction observed under a microscope. Prussian blue was produced by the oxidation of potassium ferrocyanide by ferric chloride and its product was observed to be insoluble in water 4. This was hard to observe as the reaction proceeded very quickly, as soon as the reactants touched each other the blue of the Prussian blue was observed, however the completion of the reaction was easy to observe due to the drastic colour difference. The macroscopic reactions