Presentation on theme: "Incinerating Waste Activity 26 Page B-68. Safety and Disposal You must wear protective eyewear during the activity. Copper chloride solution is toxic."— Presentation transcript:
Incinerating Waste Activity 26 Page B-68
Safety and Disposal You must wear protective eyewear during the activity. Copper chloride solution is toxic and corrosive. Avoid contact with skin and eyes. People who have an allergic reaction to the copper chloride will experience itching and redness in the affected area for a short time. Wash any affected area with water for 2–3 minutes. This activity will generate both solid and liquid waste. Dispose of all of your solutions and solids in the waste container and clean equipment as directed in Activity 23, “Producing Circuit Boards.”
Recall In the last activity you observed the products that formed during two chemical reactions, one involving copper chloride with aluminum and the other involving copper chloride with sodium hydrogen phosphate. The manufacturing of products, as in Activity 23, “Producing Circuit Boards,” also creates waste products, some of which are toxic. For computers every component manufactured—from the plastic casing to the circuit board—wastes are produced. Part of the business of manufacturing is to determine what will happen with the waste products at each life-cycle stage.
Thinking Space Question What are ways to deal with the waste created in computer manufacturing? For liquid waste, some may suggest dumping it down the drain and finding a way to recycle it. If a waste is toxic, there are limits on the amounts that can be disposed through dumping, whether down the drain or in a landfill. This protects water systems from contamination by toxic substances.
Learning Objective and Vocabulary In this activity you will observe another method of waste disposal— incineration of solid waste. Incineration is a chemical reaction called combustion, which is commonly referred to as “burning.” It converts the waste into ash, flue gas, and heat. The ash is mostly formed by the inorganic constituents of the waste, and may take the form of solid lumps or particulates carried by the flue gas into the air. Combustion is the chemical reaction that takes place when a fuel source is ignited in the presence of oxygen. You will evaluate the use of incineration for treating waste from manufacturing.
Demonstration Let’s take a look at this metal paper. This paper was made by soaking paper in a solution of concentrated copper chloride and then drying it. It represents solid wastes, including the wastes from computer manufacturing that contains metals. I will use this metal paper as one of the reactants in an incineration reaction to demonstrate one way to treat/dispose of wastes from the computer manufacturing process. First I will place the 1/2" piece in Cup A of a SEPUP tray and add 20 drops of water. As a control, I will place the 1/2" piece of nonmetal paper in Cup B, and add 20 drops of water. We have to wait approximately one minute. As we wait let’s read the introduction and challenge.
Let us now observe Cups A & B Recall the ammonia test for copper that we used in Activity 24, “Diluting the Problem.” When ammonia is used as an indicator, it reacts with copper in solution to produce a dark blue color if copper is present in concentrations higher than 100 ppm. So I will add 5–10 drops of ammonia to Cup A, and stir. Rinse the stir stick, add 5-10 drops of ammonia to Cup B, and stir. You should record the results of the ammonia test in your data table, “Testing for Copper” in your notebooks.
Results The liquid in Cup A will have turned blue, showing that copper from the metal paper is present in solution at a concentration greater than 100 ppm. Cup B will be clear in color, meaning a negative result for copper (i.e., concentration less than 100 ppm).
We can compare this to our serial dilution from Activity 23. In comparing Cups A and B with the serial dilution, you can see that the solution produced from soaking the metal paper is approximately 100,000 ppm.
Thinking Space Question: What do you know about combustion? You may have heard it related to combustion engine, Combustion chamber, and instantaneous combustion. Or that it is related to explosions. This is only partial understanding of what it is. Combustion is a chemical reaction commonly called “burning.”
Combustion The reactants of combustion are a source of stored energy (the material being burned) and oxygen, and the products are energy in the form of heat and light, carbon dioxide, and water. If the reaction is not complete, unburned matter remains in the form of ash.
Examples of Combustion Reactions candle burning, a log burning in a campfire or fireplace, charcoal glowing in a barbeque grill, or the combustion of gasoline in a combustion engine. In a combustion reaction stored energy is released as heat as the reactants react chemically. This is an exothermic reaction, as you had observed with the exothermic reaction of copper chloride and aluminum in Activity 25. “Conservation of Mass and Chemical Reactions.
Difference Between Combustion and High-Temperature Incineration In high-temperature incineration, oxygen and natural gas are added in high concentrations to make materials burn more rapidly and completely. This is similar to blowing across the paper while it burns. Adding more oxygen is one way to increase the temperature of the burning material so that it burns completely and produces less ash. The high temperature of incineration breaks complex materials down to their simpler molecules. Burning at lower temperatures leaves behind many complex substances in both the gases and ash produced
Now let’s see if copper is present elsewhere. In Part A of the Procedure- demonstrate incineration first with the metal paper by crumpling a 3” x 3” piece of metal paper and placing it on a metal pie pan resting on an insulating pad. We will light a match, and touch it to the paper in several places. The paper will burn slowly, generating ash and large amounts of smoke. As the metal paper burns, we blow air onto it. Compare the air that passes over the paper to a bellows that is used to start or keep a fire going or the process of blowing on a fire to resupply the oxygen it needs to keep reacting. The air that is added by blowing supplies fresh oxygen to the burning site and allows the paper to burn hotter and more completely. When the flame has died down, let’s observe the remaining paper smolder and the ash form. We will do this with the nonmetal paper as well.
Combustions with Science Geeks from the UK This Stuff Makes this Stuff http://youtu.be/jw3ZRmKUKyAhttp://youtu.be/jw3ZRmKUKyA Just in case the embedded code fails.
Back to Thinking Space What are the two main products of the incineration of the metal paper? ash and smoke. How did incineration change the paper? There is a small volume of ash compared to the original volume of paper. Based on what you observed, how might incineration be helpful in waste disposal? The reduction in mass and volume of the waste would be helpful because the waste would take up less space in a landfill. High temperature incineration is effective in reducing the volume of a material by nearly 75% and its mass by 80–90%.
Now the ash from each pie pan will go into an appropriate labeled plastic cups for you to use in Part B. To review the process of incineration, we will view “Waste Disposal” segment of the Issues and Physical Science DVD. This short video gives a brief overview of incineration. http://youtu.be/qn742yIHzpUhttp://youtu.be/qn742yIHzpU Just in case.
Test the smoke produced for the presence of copper. We are now going to incinerate a second piece of both the metal paper and the nonmetal paper and collect the smoke for testing. The purpose of this is to see if the metal is present in the smoke that is produced. 1 st Open a large, resealable plastic bag and place 20–25 drops of water in it. The water absorbs smoke and particles. Shake the bag to thoroughly coat the inside of the bag, and then turn the bag upside down to drain out any excess water. Crumple a piece of metal paper and light it with a match. Hold the open end of the bag about 5–6 inches above it. Pull the sides of the bag apart to collect the most smoke that you can. While filling the bag, blow gently across the paper to help it burn more completely. When the bag is full of smoke, quickly seal it
TS: What do you predict is in the smoke? Record your answer. Now to finish: Unseal a section of the zipper on the plastic bag, just large enough to fit around the dropper, and add one dropper of water. Reseal the bag, and shake it to mix the water thoroughly with the smoke particles. Hold it up for all to see. You may notice that the water has a light yellow-brown color. Think back to the incineration of the metal paper. Recall your predictions. Now…TS again: Do you think the copper from the metal paper is now present in the smoke or in the ash?
Test the smoke for the presence of copper. To do this, pour the water containing the dissolved smoke particles from the plastic bag into Cup 4 of the SEPUP tray. Add 5–10 drops of ammonia, and stir. no change in the color of the solution. The observable yellow color is a result of the smoke particles that had previously dissolved in the solution. Record the results of the ammonia test in their data table, “Testing for Copper.” Repeat the process for the nonmetal paper. should again observe that there is no change in the color of the solution.
Now what is left to test? Recall that in Activity 25, “Conservation of Mass and Chemical Reactions,” you learned that, according to the “Law of Conservation of Mass,” matter cannot be created or destroyed. TS, If the copper metal that started out in the paper is not in the smoke, what do you think happened to it? the copper must be in the ash. Now follow the Part B Procedure Steps to test the ash for copper. As you work, tell place as little of the solid in the filter paper as possible. This will help the filtration go faster.
Discussing incineration as a toxic- waste disposal method. Results indicate that the copper remained in the ash. This is one important fact of waste incineration: contents such as heavy metals do not disappear. They remain and must be considered when choosing a disposal method. Imagine the metal paper is waste sitting in a landfill. If water runs through the landfill into local water systems, it may pick up the metal in solution. Thus, incineration does not eliminate the hazards associated with the metal.
Bring out Student Sheet 24.2, “Treating Waste”
1: Which of the three items in your table, “Testing for Copper,” — paper, smoke, or ash— are products of incineration? Smoke which is CO 2 is the product. Heat and light are often represented in the chemical equation with a symbol. They are also products. Ash is the result of an incomplete reaction. For now we can consider it a product. Paper is the reactant. Oxygen is also a reactant.
2. Which of the products of incineration contained copper? Explain your evidence. The ash from the metal paper contained copper. This information is contained in students’ table, “Testing for Copper.” Site this information. After conducting the Ammonia Test the solution turned blue. This color change indicates the presence of copper just as it did in the serial dilution lab.
3. How did incineration change the metal paper? The metal paper turned into ash and smoke as it burned. It changed … color into a burnt black ash, it become smaller in volume and less dense.
4. What are the advantages and disadvantages of using incineration to dispose of heavy metals wastes? The advantages of incineration include its reduction of the mass and volume of solid waste, and its production of energy as a by-product. The disadvantages include the release of gases into the environment and the residual ash
5. Look at the information provided on Transparency 26.1, “Municipal Waste Disposal in the U.S. and Japan,” and Transparency 26.2, “Relative Landmasses of the U.S. and Japan.” Based on what you know about incineration and the information shown, why do you think these two countries handle waste disposal differently? In terms of area, Japan is slightly smaller than the state of California. It has a fairly large population relative to the United States. As a result, it has limited landfill space and incinerates most wastes.