The Copper Cycle. GSEs: Purpose. Introduction. Materials. Aura Ochoa, Trisha Sicke, Jennifer Contreras October 5, 2010 Chemistry Liz Schibuk

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1 Aura Ochoa, Trisha Sicke, Jennifer Contreras October 5, 2010 Chemistry Liz Schibuk The Copper Cycle GSEs: Science: Science Process Skills 4:12:2.2 Create written reports and journals to share and communicate scientific ideas, plans, results, and conclusions resulting from observations and investigations. Science:Science Process Skills 1:12:1.3 Make measurements and observations about a variety of events and phenomena, including those that occur during very small and very large time frames. Purpose This lab is designed around developing observation skills. Introduction In this lab, the procedure began with copper and the result was a copper-covered nickel. Despite all the materials used and steps taken, our result was the same as our beginning. This is the Copper Cycle. Despite the chemical changes and reactions, which is when a substance is changed into a different substance by mixing or heating it, the copper always remained. This is due to the Law of Conservation of Mass which states that matter cannot be created or destroyed. Each step of the Copper Cycle involved the element of copper, Cu(s), whether it was adding sodium hydroxide or sulfuric acid. Copper was always present, even if its form changed due to chemical reactions. This is because the copper in the lab could not be created or destroyed. Materials 100 ml Beaker

2 50 ml Graduated Cylinder Funnel and Filter Paper Spatula 30 ml Copper Nitrate 1 M Sulfuric Acid 1 M Sodium Hydroxide Hot Plate Zinc Fillings/Nickel Right- Stand Erlenmeyer Flask Heat-Resistant Gloves 25 ml Graduated Cylinder Procedure 1. Measure 30 ml of copper nitrate into the beaker. 2. Carefully measure 10 ml of sodium hydroxide (NaOH) into the 25 ml graduated cylinder and then pour it into beaker. Observe. 3. Place beaker on a hot plate and set it to 400 degrees and stir it until it becomes a solid. This may take 10+ minutes. 4. Use heat-resistant gloves to remove beaker from hot plate and onto lab table. 5. Filter the solution with a funnel and a piece of filter paper. *Make sure to check with Liz if you can continue or not.* 6. Using a small spatula, gently scrape the solid from paper into a 100 ml beaker. 7. Measure approximately 25 ml of 1M sulfuric acid (H 2 SO). Slowly, while stirring, add the sulfuric acid to the 100mL beaker. (Liquid Solid) 8. Add zinc filling and/or a nickel/dime to beaker. Stir the solution until it is colorless. 9. Pour away most of the liquid into the correct waste container, making sure not to pour off any of solid. 10. Add about 10 ml of water, swirl the solution, and again pour off most of the liquid into the correct container. 11. Clean up your area. Wash glassware and return equipment. Results Procedure -Used 30 ml of copper nitrate and then added 10 ml of sodium hydroxide. -Next, the beaker was placed on hot plate. - Stirred the solution for about 10 minutes and then the beaker was placed Observations -Solution turned dark blue. It became flocculent and opaque. -The solution turned into a light blue. Looks a bit flocculent. Still opaque. -The solution turned into a gray-green. It s finely divided. Has bubbles, which is a sign of gasses. Still

3 back on lab table. opaque. - Filtered the solution and then scraped -The solid is a very dark green and curdy. Opaque. solid from filter paper and put it into 100 ml beaker. -Added 25 ml of sulfuric acid to beaker. -The solution turned into a very light blue liquid. It s colloidal and a bit translucent. -Added 2/3 pieces of Zinc and a nickel. Zinc looks partly dull, partly shiny, and flaky. -Waited for a while. -The zinc turned dull and curdy, and the nickel is turning red/bronze. After a while, there are a whole bunch of particles from the zinc in the solution. -The solution colloidal again and translucent. The coin and zinc turned into a red. There are also small particles in the solution. Discussion Page 31: 1. Explain what a chemical reaction is. What are some possible signs that a chemical reaction is talking place? A chemical reaction is when a substance is changed into a different substance by mixing it with a liquid or by heating it. Some possible signs that show that a chemical reaction is taking place are color changes, release of gasses, or formation of a solid. 2. In your own words, explain how it might be possible to start with copper and end up with copper after a series of chemical reactions. It is possible to start with copper and end up with copper after a series of chemical reactions because in each step of the lab and each form that the solution went through - there was always copper. Although its form did change, whether through mixing it with other compounds or heating the solution, the element of copper, Cu, never went away. This is because according to the Law of Conservation of Mass, mass cannot be created or destroyed. 3. Look again at the copper cycle diagram. After adding zinc, the blue solution turns colorless, and copper appears as a solid. What do you think happened to the zinc? Explain your thinking. I believe that the zinc went through a chemical change. At first there were whole pieces of zinc, but after waiting a while, the whole pieces dispersed into small particles throughout the

4 solution. Although you may think that the zinc disappeared, that is not the case because matter cannot be created or destroyed. Page 37: 1. How can chemical names and symbols help you figure out what copper compound you made in each step of the copper cycle? Give an example. Although you may be able to describe in great detail what the result of a chemical reaction may look like, it would be difficult to determine which chemicals make the new substance. Due to this, chemical names and formulas are used to keep track of the starting materials and the new substances that are formed from parts of the starting materials and their state. This can help you determine which of the substances contain copper and what state the copper is in. For example, when you add sulfuric acid, H 2 SO 4 (aq), to copper oxide (CuO(s)), copper sulfate (CuSO 4 (aq)) is formed. Even if a new compound was formed, Cu (copper) was found in it. Keeping track of the steps that the chemical symbol Cu was present in proved that copper was present in every step of the Copper Cycle. 2. Explain the law conservation of mass in your own words. In my own words, I think of the law of conversation of mass as your result of something containing the same materials as you had when you began. More specifically, I think of baking as a metaphor for the law of conservation of mass. In the beginning, you mix ingredients together and your result is a pastry of your choice. Despite the pastry not looking like eggs or milk, it does in fact contain those ingredients. The form of the egg and milk might have changed after being put in an oven, but they never disappeared. You start with eggs and milk, and you end with eggs and milk. Conclusion The purpose of this lab was to develop observation skills. To be honest, prior to this lab I can say that my observations skills in science were not very developed. For example, under my data table in the procedure column, I state that my group and I set our beaker on a hot plate. From there, I had to observe the chemical reactions. Before, I probably would ve just described the solution as dark blue. Now, after learning the scientific words to use to describe precipitates, I said that the solution was light blue, flocculent, and opaque. My knowledge and vocabulary in observing expanded as the lab continued. These terms helped me observe the copper and the forms it went through, which were essential to this lab. Also, understanding how chemical symbols and formulas work and learning the law of conservation of mass, helped me determine Copper Cycle worked and be able to describe each chemical reaction that happened. If I had not

5 gained the knowledge of the specific vocabulary used for observations, chemicals formulas, and so on, I don t believe that my lab would have been as successful as it was. Having a deep understanding of what you are working on always makes your finished product much stronger.