The copper reaction experiment was demonstrated by adding the reagents like 16M HNO3, Distilled water, 6M NaOH, 6M H2SO4, Acetone, Zinc metal and Methanol into the beaker with the copper wire. The experiment was also demonstrated to observe how copper reacts while different reagents were being added. It was also demonstrated to practice the common laboratory techniques such as methods of separation involving filtration, sedimentation, decantation and extraction. While different reagents were added to the copper wire, different reactions were also observed and tallied until the recovered copper was weighed and the percentage yield was calculated from the formula: Percentage Yield=mass of recovered copperactual yieldmass of copper wire (theoretical yield) x 100
The percentage yield of the experiment was 42%.
All chemical reactions occurring within test tubes, industrial reactors, or nature, can be described by reaction equations. Knowing the skeletal reaction equation, the reactants and the products are also known, but for quantitative predictions, the reaction equation needs to be balanced. A balanced equation is an equation or a chemical reaction in which the number of atoms for each element in the reaction and the total charge are the same for both the reactants and the products. (1) From a balanced equation, the mole relationship can be figured out. The amount of product produced from a given amount of reactants based on the balanced chemical equation is referred to as the theoretical yield. The theoretical yield is based on the stoichiometry of the reaction and ideal conditions in which starting material is consumed completely, undesired side reactions do not occur, and there are no losses in the work-up procedure. On the other hand, the amount of product that is finally obtained after carrying out a reaction is called the actual yield. The percentage yield, which serves to measure the effectiveness of a synthetic procedure, is calculated by dividing the amount of the obtained product by the theoretical yield.
One or more reactants in a chemical reaction are often used in excess. The theoretical yield is therefore calculated based on the molar amount of the limiting reactant, taking into account the stoichiometry of the reaction. For the calculation, it is usually assumed that there is only one reaction involved. The ideal or theoretical yield of a chemical reaction would be 100%, a value that is impossible to achieve due to limitations in measurement accuracy. According to Vogel's Textbook of Practical Organic Chemistry, yields around 100% are called quantitative, yields above about 90% are called excellent, yields above about 80% very good, yields above about 70% are called good, yields below about 50% are called fair, yields below about 40% are called poor. Yields may appear to be above 100% when products are impure. Purification steps always lower the yield and the reported yields usually refer to the yield of the final purified product.
Materials and Methods
The prepared copper wire was weighed in an analytical balance to the nearest 0.01 g and put in a 250mL beaker. 4.0mL 16 M HNO3 is added to the beaker under the hood while it was swirled occasionally. After the reaction has completed or the copper wire has dissolved, distilled water was added to the beaker until it was half full. 30mL of 6 M NaOH was then added to the reaction mixture. The solution was heated on a Bunsen burner while constantly being stirred. When the solution has boiled, it was filtered through a filter paper. The black precipitate was washed with distilled water. The black precipitate was dissolved in 15mL 6 M H2SO4 in a 250mL beaker. 2g zinc metal was added into the reaction mixture and stirred until the...
References: 1. Chemistry Glossary, Balanced Equation Definition., About.com. http://chemistry.about.com/od/chemistryglossary/a/balanceeqdef.htm
2. Vogel, A.I., Tatchell, A.R., Furnis, B.S., Hannaford, A.J. and P.W.G. Smith. Vogel 's Textbook of Practical OrganicHall, 19936-3.
3. A. Yaksic., Chemical Reactions of Copper and Percent Yield., Retrieved August 11, 2011. http://www.yaksic.com/crcpy6.pdf
4. Analytical Balance. (2011). In Encyclopædia Britannica. Retrieved from http://www.britannica.com/EBchecked/topic/22617/analytical-balance
Please join StudyMode to read the full document