The objective of the experiment was to recover pure copper through a series of transformations. A series of chemical reactions are used to purify the copper. In the end 84 percent of the original copper was left, this means that when decanting and transferring some copper was lost.
Stoichiometry is known as the calculation of the quantities of reactants and products in a chemical reaction and in this lab one is trying to obtain the mass of copper after a series of transformations. In this experiment separation and purification are necessary to gain a product. Some ways this is done include precipitation (The process of separating a substance from a solution as a solid.), filtration (Passing a liquid through a filter to trap unwanted particles.), decantation (To pour off without disturbing the sediment.), extraction (To obtain from a substance by chemical or mechanical action, as by pressure, distillation, or evaporation.), and sublimation (To cause (a solid or gas) to change state without becoming a liquid.). Due to the law of conservation of mass one knows that the reactants are not destroyed and no new materials are created, therefore if any mass is lost it is due to human error.
A piece of copper wire with a mass of 0.098 grams was obtained. The sample was dissolved in 1 mL of concentrated nitric acid (HNO3). Next 100 mL of distilled water was added in the hood to dilute the solution along with 30 mL of sodium hydroxide. Following this 2 boiling chips were added and the mixture was heated over a meeker burner. The solution was stirred until almost boiling, at this point it was removed from the heat. Black precipitate was allowed to settle and the water was decanted into the sink and 100 mL of hot distilled water was added, and the mixture was stirred. After settling the supernatant liquid was decanted into the sink. In the hood 1 mL of 6.0 M sulfuric acid (H2SO4) was added and the mixture was stirred until the...
References: Dictionary.com. 2005. 2 Oct. 2005 .
Staff of UMass Dartmouth Chemistry and Biochemistry Dept. Laboratory Manual for
CHM: 161. North Dartmouth, MA: n.p., 2004.
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