Lab: Air Quality The intent of this lab activity is to observe and graphically analyze actual air pollution data, and to explore the sources and impacts of some key pollutants. Be sure to submit your finished assignment according to your teacher's instructions. Materials Soda bottle 1L File folder Marker Plastic cup Plastic syringe Tap Bromothymol Blue Stopwatch Vehicle Exhaust Part I: In this experiment you will measure the amount of CO2 released by a vehicle using bromothymol blue solution. This lab requires that you collect exhaust from a running car, so please take the necessary precautions. To begin you should roll the file folder into a funnel that can be used to collect the exhaust and transfer it to the empty soda bottle. Use the tape to secure your funnel in place. Select a vehicle that is a compact car, midsize car, or SUV. Once you have selected your vehicle, you should work with a partner and go to the vehicle to collect the exhaust. Have one person start the car and the other person should place the larger side of the funnel at the end of the vehicle’s muffler with the smaller side at the mouth of the soda bottle. Leave a space between the funnel and the bottle and collect the exhaust for at least 2 minutes. After you have collected the exhaust, quickly cap the soda bottle, seal it tightly, and turn off the car. The pH indicator bromothymol blue, (C27H27Br2O5SNa) changes color from blue to yellow as the acidity of the solution increases. Bromothymol blue has a pH range that is good for measuring at or near neutral (7.6 to 6.0). For this reason it is often used to observe photosynthetic and respiratory activity. When CO2 is bubbled through a solution of BTB in water, some carbonic acid is formed: CO2(g) + H2O (l) à H2CO3 (aq) Carbonic acid, H2CO3, is a weak acid that causes the pH of the solution to become acidic and the bromothymol blue solution changes color as a result. Air samples containing higher levels of CO2 will change the color closer to yellow. Take the bromothymol blue solution and add about 20ml to a plastic cup. Working with a partner, quickly take the cap off the soda bottle and insert the plastic syringe. Collect a 50ml air sample by pulling the plunger back on the syringe while gently squeezing the soda bottle. Quickly place the cap back on the soda bottle. Insert the tip of the syringe into the cup with the bromothymol blue solution and release 25ml of exhaust into the solution. Record the color of the solution and be prepared to discuss the color change. Part II: What do you believe you will see as a trend for 1970 to 2011 for the following pollutants: carbon monoxide, nitrogen oxides, sulfur dioxide and volatile organic compounds (VOCs)? The second portion of this lab will allow you to practice analyzing real pollution data. What are the most common pollutants the EPA recognize as a source of air pollutants? On your own paper, create and complete the chart below using following websites or any additional resources. a. EPA’s Six "criteria" pollutants http://www.epa.gov/air/urbanair/ b. CA Ambient Air Quality Standards http://home.lcusd.net/lchs/mewoldsen/APES/Unit12/CA_Am
bient_Air_Quality_Standards.htm POLLUTANT FACTS Carbon Monoxide Nitrogen Oxides Lead Particulate Matter 10 Ozone Particulate Matter 2.5 Sulfur Dioxide VOCs Sources (primary or secondary & chemistry involved) Health Effects Environmental Effects 1970 – 2011 Trend (from your graph) EPA Air Quality Trend Next, make two XY Scatter Line graphs of the 1970 – 2011 Air Pollution Data shown below using MS Excel or a graphing website like http://www.onlinecharttool.com/ Analysis What color was your bromothymol blue solution after you added the vehicle exhaust? How do you think this relates to the kind of vehicle exhaust collected? How would you expect the CO2 emissions of your car to rank compared to other vehicles? Why? Graph using the Raw Data totals with all pollution data. Next, graph using percentage of 1990 value with all pollution data. Describe the differences in the graphs you created – Is one easier to see trends? Are there any significant changes in any of the pollutants over the years? If so, which ones and what do you think caused those increases? Decreases? Familiarize yourself with the lab report rubric on the next page. This is the rubric that will be used to grade this assignment and throughout the course, so be sure to review it carefully. AP Environmental Science Lab Report Rubric When you complete your lab reports for this course, you will need to follow the guidelines included in the rubric below. Be sure to label each section of your lab report accordingly. Points Possible Title Prepare a specific and appropriate title that briefly describes the scope and purpose of your investigation. 5 Introduction Develop 1-­‐2 informative paragraphs that describe the initial observations; problem statement; background information including important terms and key points related to the investigation; the purpose of the investigation and how it relates to the topic of study; and a testable hypothesis written in an if/then/because or null/alternative format. Materials & Procedures Compile a complete listing of the materials and supplies used with the exact steps followed to conduct the investigation. The narrative should include enough detail in the experimental design so that others can duplicate the investigation. Be sure to identify the control, variables, and the measurement techniques used. Data Collection Record all qualitative and quantitative data collected during the investigation. Data should include raw data, field notes, pictures, or drawings presented in appropriately labeled data tables or diagrams. Analysis & Discussion Summarize results as an explanation of the data as presented in the appropriate graphs and charts. Graphs must include descriptive titles, axes labels, and a legend if necessary. All mathematical determinations should be figured with complete formulas and error analysis as necessary. Required questions and answers must be included. Show all calculations, including equations and computation. Conclusion Describe what your findings mean and relate them to conclusions you can draw from the data. Give valid explanation based on correct interpretation of results in relation to hypothesis. Where appropriate, compare results with accepted values. Evaluate procedure and results to discuss limitations, weaknesses, or sources of error. State realistic suggestions to improve the investigation and questions for further investigation. Points Earned 15 10 20 25 15 Formatting Paper is properly formatted following class guidelines for font, margin and page settings. All lab reports should include in-­‐text citations and references to acknowledge the sources used to support findings and explanations. 10 Total Points 100