Stem Lab Environmental Engineering Concentration of Ear ✓ Solved

Earth’s atmosphere is a mixture of gases. About 99 percent of the atmosphere is made up of nitrogen and oxygen. Certain other gases present in smaller amounts are critical to Earth processes. Water vapor and carbon dioxide gas are important in regulating the amount of energy absorbed by the atmosphere. Ozone gas helps control the amount of ultraviolet radiation that reaches Earth’s surface.

Scientists are particularly interested in measuring changes in the amounts of greenhouse gases, including water vapor, carbon dioxide, methane, and nitrous oxide. These gases occur in such small amounts in the atmosphere that scientists describe their concentration in units of parts per million (ppm), or even parts per billion (ppb). Imagine pouring one can of soda into a large swimming pool, and you are thinking on the order of parts per million. If you can imagine adding one pinch of salt to 10 tons of potato chips, you’re thinking on the order of parts per billion! In this activity, you will simulate dilution of a substance to extremely small concentrations. After calculating these concentrations, you will relate the data to the concentration of important gases in Earth’s atmosphere.

OBJECTIVES Describe the meaning of the units parts per million and parts per billion. Explain why these units are used to describe the concentration of some atmospheric gases. Create solutions of diminishing concentration. Compare the concentration of solutions created in the experiment to the concentration of certain atmospheric gases.

MATERIALS USED IN ACTUAL LAB IF DONE IN PERSON • eyedropper or pipette • food coloring • ice cube tray white, or clear plastic trays with white paper underneath • marker, permanent • plastic cups, small (3) • water jug, filled with water.

Procedure for actual lab if done in person 1. Use the marker to number the outside of each section of the ice cube tray from 1 to 10. Each section is a “cell” in which you will create a solution with a certain concentration. 2. Fill the three plastic cups about half full with water. The water will be used for cleaning the eyedropper or pipette during the experiment. Concentration of Earth’s Greenhouse Gases continued 3. Put 10 drops of food coloring in cell #1. The concentration of this substance is 1 million parts per million. It represents a pure substance. Write the concentration of this substance as a fraction. Examine how this data has been recorded in Table 1. TABLE 1: FOOD COLORING CONCENTRATION Cell Number Food Coloring Concentration (parts per million).

Take one drop of food coloring from cell #1 and add it to cell #2. Rinse the dropper in one of the plastic cups until all traces of food coloring are removed. Add 9 drops of clean water to cell #2 and stir. The mixture is now diluted to the concentration of the original substance. The concentration of the new substance is 100,000 parts of food coloring per million parts of solution. Write the concentration of the substance as a fraction. Examine how this data has been recorded in Table 1.

Take one drop from cell #2 and add it to cell #3. Rinse the dropper completely. Add 9 drops of clean water to cell #3 and stir. How has the food coloring concentration changed? Record the food coloring concentration of cell #3 in Table 1. 6. Repeat this procedure for cells 4 through 10. Record the concentration of each cell in Table 1. 7. Greenhouse gases affect the temperature of Earth’s atmosphere. Study Table 2 on the following page, which shows the concentrations of these gases. Use the information given, as well as the data from Table 1, to determine which of the food coloring cells is closest in concentration to the concentration of each greenhouse gas.

Concentration of Earth’s Greenhouse Gases continued TABLE 2: CONCENTRATION OF GREENHOUSES GASES IN EARTH’S ATMOSPHERE Gas Concentration Cell Number Carbon dioxide 355 ppm Methane 1.7 ppm Nitrous oxide 0.3 ppm Chlorofluorocarbon-.0005 ppm Chlorofluorocarbon-.0003 ppm Analysis 1. Describing Events What changes did you notice in the concentration of the solutions you created as you moved from cell #1 to cell #10?

2. Explaining Events Some of the solutions created were colorless. Each 1/10 dilution you made diluted the color of the food coloring, and hence the concentration. Was there any food coloring in those cells? How do you know? Conclusions 3. Drawing Conclusions Imagine that the food coloring in the experiment represents carbon dioxide. What do the water drops added to each cell represent? Extension 1. Research and Communication The concentration of each greenhouse gas in parts per million is incredibly small. How can gases that have such small concentrations have such a large impact on Earth’s atmosphere? Use library resources to research one greenhouse gas. In written or oral form, describe the role this gas plays in Earth’s atmosphere.

Paper For Above Instructions

The Earth's atmosphere acts as a blanket, regulating temperature and facilitating life through a complex mixture of gases, predominantly nitrogen (78%) and oxygen (21%). However, in much smaller quantities, greenhouse gases such as carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O) play a crucial role in earth's climate system. With increasing levels of these gases due to human activities, understanding their concentrations becomes paramount.

The terms "parts per million" (ppm) and "parts per billion" (ppb) are utilized to express the amounts of these greenhouse gases in the atmosphere due to their extremely low concentrations. For instance, the measurement of carbon dioxide levels at 355 ppm means that for every million air molecules, 355 are CO₂ molecules (National Oceanic and Atmospheric Administration, 2020). This unit of measurement gives context to the discussion about climate change, as it helps to gauge the intensity of greenhouse effects contributed by these gases.

To visualize these concepts, an experiment can simulate the process of dilution. By creating a series of diluted food coloring solutions, one can observe how concentrations decrease. For instance, beginning with 10 drops of food coloring (1,000,000 ppm), each successive dilution reduces the food coloring concentration by a factor of ten. This process mirrors rising and falling concentrations of atmospheric greenhouse gases due to various climatic processes.

As stated in the lab scenario, starting with a concentrated solution then diluting it across several cells demonstrates the concept of diminishing concentrations effectively. The initial cell might represent a high concentration of carbon dioxide found in urban areas, while the final cell could represent rural areas with significantly less CO₂ concentration due to vegetation, which absorbs CO₂ through photosynthesis (IPCC, 2021).

A comparative analysis of the prepared solutions would involve relating the food coloring cell concentrations to the atmospheric concentrations of greenhouse gases outlined in Table 2. For instance, the cell with a concentration close to 355 ppm of CO₂ would be aligned with the first few diluted solutions, while lower concentrations of methane (1.7 ppm) and nitrous oxide (0.3 ppm) may correspond with the higher dilution cells.

One prominent greenhouse gas, methane, possesses the potential to trap heat in the atmosphere significantly more effectively than carbon dioxide, despite existing in lower concentrations. It is estimated that methane is over 25 times more effective than CO₂ at trapping heat over a 100-year period (Intergovernmental Panel on Climate Change, 2021). This emphasizes the need to monitor even the lowest concentrations of greenhouse gases due to their substantial long-term climatic impact.

Moreover, nitrous oxide, while present in trace amounts (0.3 ppm), has a greenhouse effect that is about 298 times more potent than that of carbon dioxide (United States Environmental Protection Agency, 2022). Thus, understanding how these gases behave – even at low concentrations – is fundamental to manipulating future climate models and addressing climate change.

The implications of these small concentrations can be understood through research. According to the Global Carbon Project, CO₂ levels have risen by over 40% since the industrial revolution, highlighting the exacerbation of the greenhouse effect (Global Carbon Project, 2020). Furthermore, studies show that even minor increases in these gases can lead to pronounced changes in global temperatures, precipitation patterns, and atmospheric chemistry (National Aeronautics and Space Administration, 2021).

In conclusion, while greenhouse gases exist in incredibly small concentrations, their roles cannot be underplayed. As demonstrated in the lab, understanding their concentrations through terms like ppm and ppb is essential to grasping their impact on Earth's climate. Through careful monitoring and research, we can work toward mitigating their effects on the environment.

References

• Global Carbon Project. (2020). Global Carbon Budget 2020. Retrieved from http://www.globalcarbonproject.org
• Intergovernmental Panel on Climate Change. (2021). Sixth Assessment Report. Retrieved from https://www.ipcc.ch/report/ar6/wg1/
• National Aeronautics and Space Administration. (2021). Climate Change: How Do We Know? Retrieved from https://climate.nasa.gov/evidence/
• National Oceanic and Atmospheric Administration. (2020). Trends in Atmospheric Carbon Dioxide. Retrieved from https://www.esrl.noaa.gov/gmd/ccgg/trends/
• United States Environmental Protection Agency. (2022). Inventory of U.S. Greenhouse Gas Emissions and Sinks. Retrieved from https://www.epa.gov/ghgemissions/inventory-us-greenhouse-gas-emissions-and-sinks