Expirement 8: The Copper Cycle

GRADING RUBRIC EXPERIMENT 8 – LAB REPORT Write-up (80 pts) Day & time of the lab: ____3/29/22 9 AM_______________________ The lab report packet for this experiment should consist of the following in THIS ORDER: The lab report packet for this experiment should consist of the following: 1. (10 pts) IN-lab notebook pages 1.1. Experimental procedure 1.2. Detailed observations 2. (70 pts) The Write-up 2.1. (15 pts) Introduction 2.2. (50 pts) Results & discussion 2.3. (5 pts) References Complete this worksheet and turn in your digital lab packet to Canvas. Feel free to adjust space in this document as needed. The tables provided here are only an example of these may look like, feel free to replace the entire tables with your own creations using Excel, etc All tables and figures (graphs) must be accompanied by captions which should be positioned above tables and below figures. TURN IN the digital copy to Canvas on the due date by 11:59 pm. All electronic material must be completed by the due date to avoid late penalties. 1 (15 pts) INTRODUCTION 2 (5 pts) Include at least two recent journal references (published within the last year or two) with research relevant to types of reactions or methods used in this lab. (5 pts) Include and discuss at least two historical perspectives or applications using two additional journal references. (5 pts) Discuss the purpose and specific objectives of this experiment. This is similar to the first pre-lab question, but not identical (past tense, third person). The copper cycle experiment strived to produce four different copper compounds through a series of reactions with metallic copper, Cu(s), and different reagents that was conducted before returning to its original form that is metallic. Observations were recorded for all the chemical and physical changes in each reaction and the balanced chemical reaction for each reaction is written and classified. Lastly, the percent recovery of the final copper product was determined. Moreover, the copper cycle lab aimed to perform of a series of precipitation, acid-base, decomposition, and redox reactions on successive copper-based compounds, calculate the percent recovery of the final copper product, and compose 5 balanced chemical equations and necessary sub-equations from the classification of each reaction in the cycle. In a recent article, from the Environmental Science and Pollution Research, obtaining chloride ions through fly ash washing was discussed. In fly ash, soluble and insoluble chloride ions can be obtained which can be dangerous if handled improperly because it can corrode buildings and be harmful to health. Thus, through fly ash washing, chloride ions can be obtained. Similar to the copper cycle experiment, the purpose of washing a solid is to remove any unwanted compounds, therefore, through washing fly ash, chloride ions which are unwanted can be removed. In order to wash the fly ash, the ash was weighed and added to a reaction kettle to which deionized water was added then mixed with a stirrer. The stirring speed was set to 170 ± 10 r/min. The mixed solution was then poured into a Buchner funnel with two layers of 0.45 µm filter membrane for vacuum filtration. The ash is then placed to dry and the Clconcentration is measured. In the copper cycle experiment, the concentration of a specific component was not measured after washing, but the purpose of washing was to eliminate an unwanted compound. Thus, both experiments are similar in a sense because the purpose was to rid the solid of unwanted materials as that is the purpose of ‘washing’. In another recent article regarding the steel tempering discusses the precipitation reaction of 9Cr1.5Mo1CoB(FB2). With that being said, this experiment was conducted through first tempering FB2 steel. This steel was cut and then homogenized at 1100 ° C and then cooled to room temperature by water. It should be noted that the steel was tempered at an array of different temperatures: 500 ° C, 600 ° C, and 700 ° C. When looking at the results from the SEM and TEM technology results it can be concluded that water cooling after normalization at 1100 °C creates lathy martensite. Additonally, when increasing in temperature from 600 ° C to 700 ° C (Cr,Mo)2(C,B) and Cr-rich M7(C,B)3 in the martsenite is replaced by Cr-rich M23(C,B)6. Thus, it can be seen that when tempering steel at an array of different temperatures a precipitate can form. Similar to the copper cycle lab, the precipitate was able to form after heat was applied and then cooled. Thus, even though these two experiments are drastically different they are similar in the way the precipitate is created, meaning that the heat applied and the cooling process is what creates the precipitate. An article written by H.Tillisch in 1918 discusses a technique used to decant liquid that is supposed to significantly decrease decanting time. This technique that Tillisch discusses is in regards to angling the glassware so the solid remains in the bottom portion of the glassware, leaving only the liquid to pour out. Tillisch states that by angling the “tube”, the glassware he was experimenting with, at a 45 ° angle, the liquid is able to form a channel, allowing the solid 3 and liquid to be completely separated. Moreover, he states that with this method, the decanting time can be finished within one -third of the time it takes by pipetting the liquid out. Additionally, he mentions that this a common practice for tubes. Within the means of the copper cycle lab, this could also be applied when decanting the fluid from washing the new metallic copper as the copper was dense enough to not spill or get mixed with the washing fluid. Therefore, this method can be applied within this lab as there are many portions within the lab where decanting was necessary, however, that can be very time intensive. Thus, by finding a specific angle in which the decanting fluid and the precipitate are completely separate, ensuring the product will not spill into the waste beaker, a lot of time can be saved. George E. Rouse wrote an article in 1951 describes the experiments and results of a new steam bath technique to reduce evaporation time. It was stated that one of the main reasons the evaporation time takes a significant amount of time is due to the uneven dispersal of heat. The heat of the steam bath is concentrated to the only the bottom of solution which makes there an uneven drying time, increasing the overall evaporation time. Thus, Rouse concluded that if the heat could also be applied to the sides, the evaporation of the solution would be more rapid. With that being said, two trials were conducted to deduce which method would result in a more efficient drying time: a bath with the bottom part of the beaker touching the boiling water but top edges surrounded with steam and a bath with only steam surrounding the beaker. It was found that the beaker with its bottom touching the bottom beaker evaporated 51% faster than the steam surrounding beaker. Although, in the copper cycle an evaporating dish was used instead of a beaker, the same concept can still be applied. A smaller dish allows the heat of the beaker to be more dispersed within the dish which allows for a faster evaporation time. In comparison, if the copper that was produced was placed into a larger beaker, it can be assumed the evaporation time would be longer because the heat would have to disperse to more places. Therefore, the more places the heat can touch the less evaporation time is needed. (50 pts) RESULTS & DISCUSSION **Material can be presented in any order** The results and discussion sections should be written in an essay format. Discussion questions may not be numbered and can be answered in any order. Individual chemical equations should be formatted on separate lines. Feel free to use the example tables below or make your own; adjust the captions as you see fit. (6 pts) Complete Data Table 1 and Data Table 2 based on your data. Include them both in your discussion where relevant. Table 1. Initial and final masses of Cu(s). Description Mass (g) Cu(s) wire .419 Evaporating dish 21.708 4 Evap. dish + Cu(s) product Cu(s) product 22.024 .316 Table 2. Observations for Reactions 1-5. (This should be a combination of observations you made while performing the experiment and the photos you took of each product) Reactio Product Observations n 1 Cu(NO3) 2 Solution first turned green with yellow portions after adding 16 M HNO3. Brown fumes began to be released from the solution. Which is NO2, a toxic fume. The solution needed to be swirled several times for the copper wire to fully dissolve. After the reaction was complete and there was no more toxic gas, the solution was a dark teal color to which turned a blue-green after adding water. 5 2 Cu(OH)2 When adding NaOH to the blue green solution of the Cu(NO3)2 , the solution turned from a light teal color to a cloudy blue. It can be visibly seen that there some substance within the solution that is making the solution turn cloudy. Additonally, the Ph paper shows that this is a basic solution as it is a dark blue on the paper, which is a pH between 11 and 12. 6 3 CuO The cloudy blue solution slowly became a dark green color which eventually turned into a dark green-brown with precipitate. For the precipitate to form on the hot plate, it took approximately 25 minutes and approximately 10 minutes for the solution to settle. 4 CuSO4 7 After adding the 15 mL of H2SO4 the solution turned to light aqua color immediately, the precipitate seemed like it dissolved. 8 5 Cu(s) Aluminum wire slightly dissolved and turned aqua blue solution into a very cloudy grey solution. After removing the wire and decanting, large copper pieces were left. Decanting turned waste solution clear. Additionally, drying the copper in the steam bath created the copper to have a powder consistency. In reaction 1 the mass of a copper wire was weighed and recorded, .419 g. Next, the wire was placed in a 250 mL and needed to be bent in a circular shape so it would lay flat in the beaker. After the wire was able to lay flat in the beaker, 4 mL of 16 M HNO3 was obtained and added to the beaker with the wire. After the 16 M HNO3 was added NO2 was formed which is a dangerous gas. The reaction is complete once there is no more NO2 , and because this gas was produced it demonstrates that reaction 1 is an exothermic reaction as the brown gas is also heat. The reaction eventually turned into a dark teal color, which took approximately 10 minutes, but then became a light teal color once 150 mL of DI water 9 was added. In reaction 2 NaOH was added to the final light teal solution in reaction 1, which caused a chemical change and turned the solution from a light teal blue to a dark cloudy blue. This reaction also released heat, indicating it is an exothermic reaction. The pH paper indicates that this a basic solution because the paper turned a dark blue which indicates that the solution is between 11-12 pH. Reaction 3 begins with the final cloudy blue solution in the end of reaction 2, which is then placed on a hot plate and heated. Because heat was added to the solution, this is an endothermic reaction. The reaction gradually started getting darker in color and became this dark brown/black color. When the solution became very dark, brown or black, the beaker was removed from the hot plate and began to wait for the precipitate that was formed in the beaker to settle. When the precipitate settled, there was a separation as the fluid above the precipitate was clear. This difference indicates that the precipitate is insoluble which is why it became a solid. The clear liquid was decanted and placed in a waste beaker, the precipitate was washed and decanted two times, leaving the final product to be precipitate and left over washing solution that could not be decanted. Next, in reaction 4, H 2SO4 was added to the precipitate which caused the black precipitate to almost immediately dissolve and turn back into the original light teal color in reaction 1.This was an exothermic reaction because heat was given off when the H2SO4 was added. In reaction 5, an aluminum was added to the beaker for the formation of solid copper on the aluminum wire. This solution was also gently heated and constantly heated until the solution became very cloudy, and grey in color. The solution that is not the copper is decanted while the copper was retrieved and placed in an evaporating dish. A steam bath was also prepared to the dry copper and the copper solid was washed with water 3 times with 5 mL portions. After the copper was washed, it was placed on top of the steam bath to dry which took approximately 4 minutes and gave the copper a powdery texture. Reaction 1 was a redox reaction and the equations are as follows: Balanced chemical equation: Cu(s) + 4HNO3 (aq) -> Cu(NO3)2 (aq) + 2NO2(g) + 2H2O(l) Copper oxidation: Cu -> Cu2+ + 2eNitrogen reduction: NO3- + 2H+ + 2e- -> 2 NO2 + H2O The oxidizing agent is HNO3 while the reducing agent is Cu. Reaction 2 was a precipitation reaction and the equation are shown below: 10 Balanced formula unit: Cu(NO3)2(aq) + 2NaOH(aq) -> Cu(OH)2(s) + 2NaNO3(aq) Total ionic: Cu2+ (aq) + 2NO3(aq) + 2Na+(aq) + 2 OH-(aq) -> Cu(OH)2(s) + 2Na+(aq) + 2NO3- (aq) Net ionic: Cu2+ (aq) + 2OH-(aq) -> Cu(OH)2(s) Reaction 3 was a decomposition reaction and the equation is shown below: Balanced chemical equation: Cu(OH)2(s) -> CuO(s) + H2O(l) Reaction 4 was an Acid-Base Reaction and the equations are shown below: Balanced Formula Unit: CuO(s) + H2SO4(aq) -> CuSO4(aq) +H2O(l) Total ionic: CuO(s) + 2H+(aq) + SO42-(aq) -> Cu2+(aq) +SO2-4(aq) + H2O(l) Net ionic: Cu(O)(s) + 2H+(aq) -> Cu2+(aq) + H2O(l) Reaction 5 was a redox reaction, the equations are as follows: Full Balanced Chemical Equation: 3CuSO4(aq) + 2Al(s) _> 3Cu(s) + Al2(SO4)3(aq) Aluminum oxidation: Al -> Al3+ + 3e Copper reduction: 11 Cu2+ + 2e- -> Cu The reducing agent is Al(s) while the oxidizing agent is CuSO4(aq). The compounds that were being removed when the recovered copper product was being washed repeatedly with water aluminum salts and unreacted copper sulfate were being removed. This was done through washing the water repeatedly with hot water that was previously heated on the hot plate. In doing so, the Copper could then be washed with ethanol to decrease the evaporating time, then heated and weighed. Ethanol has a lower boiling point than water so when placed on the evaporating dish, the ethanol is able to evaporate faster than water would have. Additionally, a steam bath was used in reaction 5 because it allowed for more control over the evaporation speed than a hot plate would. If the copper had been put on a hot plate to evaporate, the product could have overheated which would lead the Cu(s) to oxidize by reacting with atmospheric oxygen. The % recovery for the copper based on the assigned data is 75.4% which is below 100%. The Law of Conservation of Mass states that in a chemical reaction mass is neither gained nor lost. One plausible explanation to why the % recovery is not exactly 100% is that some of the black precipitate could have been decanted when trying to decant the colorless solution in reaction 3. Thus, there would be a loss of product, explaining why not all of the product is recovered. Additionally, another explanation of why the percent recovery is not exactly 100% is that in the formation of Cu(s), the reaction could have not have been fully completed and not scraping all of the metallic copper from the aluminum wire could also lead to a loss of product. Therefore, there is a decrease in the product which then decreased the product recovery from being 100%. A reasonable error that could cause a high percent yield, which is over 100%, would the ethanol not completely evaporating which would account for some of the final mass. Another plausible explanation would be overheating the solution to oxidize meaning that more electrons would be added to the final product, making the mass larger than the initial mass. A reasonable error that could also cause a low percent yield would be not adding enough HCl which would result in the reaction not completing to its fullest potential. . Another reason for a low percent yield is when the wire is reacting, there could be residue or some particles that are still left on the sides of the beaker. = REFERENCES – 5 pts Include at least four outside references, not including the ones used for the lab manual. 12 J. Chem. Educ. 1951, 28, 6, 327 Publication Date:June 1, 1951 https://doi.org/10.1021/ed028p327 © American Chemical Society and Division of Chemical Education, Inc. Journal of Chemical Education 1951, 28, 6, 327 (Article) Publication Date (Print):June 1, 1951DOI: 10.1021/ed028p327Huang, H., Liu, W., Zhang, L. et al. A microscopic and quantitative analysis on the separation of chloride ion by fly ash washing: Effect of liquid-to-solid ratio, washing time and temperature. Environ Sci Pollut Res (2022). https://doi.org/10.1007/s11356-021-18390-6 Yongqiang Zhang, Jianfeng Gu, Lizhan Han, Elemental redistribution and precipitation reactions of 9Cr1.5Mo1CoB(FB2) steel during tempering, Materials Characterization, Volume 171, 2021, Ind. Eng. Chem. 1918, 10, 8, 631 Publication Date:August 1, 1918 https://doi.org/10.1021/ie50104a027 13