ULO-3a Atmosphere Chemistry PDF

College of Engineering Education 2nd Floor, BE Building Matina Campus...

College of Engineering Education 2nd Floor, BE Building Matina Campus, Davao City Telefax: (082)296-1084 Phone No.: (082)300-5456/300-0647 Local 133 Big Picture 3 Week 6-7: Unit Learning Outcomes (ULO): At the end of the unit, you are expected to a. demonstrate understanding on the chemistry of atmosphere; b. explain the chemistry of water; c. show understanding of the concept of soil chemistry. Big Picture in Focus: ULO3a. demonstrate understanding on the chemistry of atmosphere Metalanguage In this section, the most essential principles and concepts relevant to the study of the chemistry of atmosphere to demonstrate ULO3a will be reviewed. Please refer to these definitions in case you will encounter difficulty in the in understanding educational concepts. Acid Rain rain, or precipitation, with a pH of 5.6 or lower. It is caused by the pollutants sulfur dioxide and nitric oxides. Ammonification a process when an organism excretes waste or dies, the nitrogen in its tissues is in the form of organic nitrogen (e.g. amino acids, DNA) Assimilation the formation of organic nitrogen compounds like amino acids from inorganic nitrogen compounds present in the environment. Organisms like plants, fungi and certain bacteria that cannot fix nitrogen gas depend on the ability to assimilate nitrate or ammonia for their needs. Combustion or burning, is a high-temperature exothermic redox chemical reaction between a fuel and an oxidant, usually atmospheric oxygen, that produces oxidized, often gaseous products, in a mixture termed as smoke. Conduction the transfer of heat energy through matter from particle to particle; most effective in solids Convection the transfer of heat energy in gases or liquids due to density differences Coriolis Effect an effect whereby a mass moving in a rotating system experiences a force (the Coriolis force) acting perpendicular to the 132  College of Engineering Education 2nd Floor, BE Building Matina Campus, Davao City Telefax: (082)296-1084 Phone No.: (082)300-5456/300-0647 Local 133 direction of motion and to the axis of rotation. On the earth, the effect tends to deflect moving objects to the right in the northern hemisphere and to the left in the southern and is important in the formation of cyclonic weather systems. Denitrification the process that converts nitrate to nitrogen gas, thus removing bioavailable nitrogen and returning it to the atmosphere Exosphere a thin, atmosphere-like volume surrounding a planet or natural satellite where molecules are gravitationally bound to that body, but where the density is too low for them to behave as a gas by colliding with each other. Humidity the amount of water vapor in the atmosphere at a given location on Earth’s surface Ionosphere the layer of the earth's atmosphere that contains a high concentration of ions and free electrons and is able to reflect radio waves. It lies above the mesosphere and extends from about 50 to 600 miles (80 to 1,000 km) above the earth's surface. Latitude an angle (defined below) which ranges from 0° at the Equator to 90° (North or South) at the poles. Lines of constant latitude, or parallels, run east–west as circles parallel to the equator. Longitude a geographic coordinate that specifies the east–west position of a point on the Earth's surface, or the surface of a celestial body. It is an angular measurement, usually expressed in degrees and denoted by the Greek letter lambda. Meridians connect points with the same longitude. Mesosphere the third layer of the atmosphere, directly above the stratosphere and directly below the thermosphere. In the mesosphere, temperature decreases as altitude increases. Nitrification the process that converts ammonia to nitrite and then to nitrate Nitrogen fixation the process of converting N2 into biologically available nitrogen Ozone also called trioxygen; an inorganic molecule with the chemical formula O₃; a pale blue gas with a distinctively pungent smell. Radiation waves that directly transport energy through space; brings heat to our planet. Smog fog or haze combined with smoke and other atmospheric pollutants. Soot a black powdery or flaky substance consisting largely of amorphous carbon Stratosphere the second layer of the atmosphere, it is just above the troposphere Thermosphere the layer in the Earth's atmosphere directly above the mesosphere and below the exosphere. Within this layer of the atmosphere, ultraviolet radiation causes photoionization/photodissociation of molecules, creating ions in the ionosphere. Troposphere the lowest part of the Earth's atmosphere 133  College of Engineering Education 2nd Floor, BE Building Matina Campus, Davao City Telefax: (082)296-1084 Phone No.: (082)300-5456/300-0647 Local 133 Essential Knowledge Atmospheric Chemistry According to Dharmesh Patel (2016), atmospheric chemistry studies the chemical composition of the natural atmosphere, the way gases, liquids, and solids in the atmosphere interact with one another and with the Earth's surface and associated biota. This field is also concerned with how the activities of the human race changed or is changing the both physical and chemical characteristics of the atmosphere. It is a multidisciplinary approach of research and draws on: Environmental Chemistry, Physics, Meteorology, Computer Molding, Oceanography, Geology, Volcanology and etc. The composition of the Earth's atmosphere changes as result of natural processes such as volcano emissions and lightning. But, it has also been changed by human activity and these changes are harmful to human health, crops, and, ecosystems. Some of the problems addressed by atmospheric chemistry include acid rain, ozone depletion, photochemical smog, greenhouse gases, and global warming. LAYERS OF THE ATMOSPHERE The lowest part of the Earth's atmosphere is referred to Troposphere. It harbors about every single living thing and almost all human activity. It is also the area of atmosphere where the weather occurs. The temperature in this area decreases as the altitude increases. Stratosphere is the second layer of the atmosphere; it is just above the troposphere. It is also where the ozone can be found. Unlike the troposphere, stratosphere temperature increases as the altitude decreases. The third layer of the atmosphere is Mesosphere. Similar to troposphere, as you get higher, the temperature gets colder. Thermosphere is the next layer above the mesosphere. It has a very thin air. It is also where the ionosphere located. Ionosphere is full of electrically charged ions. The UV rays ionizes these gases. 134  College of Engineering Education 2nd Floor, BE Building Matina Campus, Davao City Telefax: (082)296-1084 Phone No.: (082)300-5456/300-0647 Local 133 Exosphere is the outermost layer of the atmosphere. It extends up to 10,000 km above the surface. (Cassie’s Chemistry) COMPOSITION OF THE ATMOSPHERE Early Atmosphere 4.7 billion years ago, volcanic activity formed the Earth’s atmosphere and mainly composed of carbon dioxide (CO2), water vapour (H2O), methane (CH4), and ammonia (NH3). As the Earth cooled, the water vapour (H2O) condensed and formed the oceans. This result to bacteria, algae and small organism to evolve and carried out the process called photosynthesis. Carbon dioxide (CO2) dissolved in the oceans and was taken by organism and eventually "locked up" in sedimentary rocks and fossil fuels. As plant evolved, photosynthesis took CO2 and produced O2. Other gases such as methane (CH4) and ammonia (NH3) decreased as they reacted with oxygen. As for nitrogen (N2), it is very unreactive so it has built up over time. Today’s Atmosphere The changes in the early atmosphere resulted to the atmosphere in the present. The atmosphere today is mostly nitrogen (N2) and oxygen (O2) with very small amounts of other gases such as water vapour (H2O), carbon dioxide (CO2) and noble gases such as argon, neon, xenon, and krypton. The Pie chart shows the percentage by mass of the composition of a dry air atmosphere. 135  College of Engineering Education 2nd Floor, BE Building Matina Campus, Davao City Telefax: (082)296-1084 Phone No.: (082)300-5456/300-0647 Local 133 NITROGEN CYCLE Nitrogen (N2) molecules can't be utilize straightforwardly by plant or creatures. It also held by a very strond triple bond. Thus, there is a process that an organism needed to do. (Hill, 2013) According to Bernhard (2010), the major transformations of nitrogen are nitrogen fixation, assimilation, nitrification, denitrification, and ammonification. Nitrogen Fixation is the process of converting N2 into biologically available nitrogen. Although most nitrogen fixation is done by prokaryotes, some nitrogen can be settled abiotically by lightning or certain modern procedures, including the burning of fossil fuels. In Assimilation, plants can absorb nitrate or ammonium from the soil by their root hairs. If nitrate is absorbed, it is first reduced to nitrite ions and then ammonium ions for incorporation into amino acids, nucleic acids, and chlorophyll. In plants that have a symbiotic relationship with rhizobia, some nitrogen is assimilated in the form of ammonium ions directly from the nodules. It is now known that there is a more complex cycling of amino acids between Rhizobia bacteroids and plants. The plant provides amino acids to the bacteroids so ammonia assimilation is not required and the bacteroids pass amino acids (with the newly fixed nitrogen) back to the plant, thus forming an interdependent relationship. While many animals, fungi, and other heterotrophic organisms obtain nitrogen by ingestion of amino acids, nucleotides, and other small organic molecules, other heterotrophs (including many bacteria) are able to utilize inorganic compounds, such as ammonium as sole N sources. Utilization of various N sources is carefully regulated in all organisms. Nitrification is the process that converts ammonia to nitrite and then to nitrate. Anammox bacteria oxidize ammonia by utilizing nitrite as the electron acceptor to produce gaseous nitrogen. Denitrification the process that converts nitrate to nitrogen gas, thus removing bioavailable nitrogen and returning it to the atmosphere. Ammonification, it is a process when an organism excretes waste or dies, the nitrogen in its tissues is in the form of organic nitrogen (e.g. amino acids, DNA). Various fungi and prokaryotes then decompose the tissue and release inorganic nitrogen back into the ecosystem as ammonia. 136  College of Engineering Education 2nd Floor, BE Building Matina Campus, Davao City Telefax: (082)296-1084 Phone No.: (082)300-5456/300-0647 Local 133 OXYGEN CYCLE Plants are the main creators of oxygen in the atmosphere through the process of photosynthesis. Plant uses sunlight and carbon dioxide to produce energy and releases oxygen. Animals breathe in the oxygen and then breathe out carbon dioxide. The plant can then use this carbon dioxide and the cycle is complete. Processes That Use Oxygen: Respiration - animals and plants use up oxygen when they breathe. Decomposing - When plants and animals die, they decompose. This process uses up oxygen and releases carbon dioxide. Rusting - This is also called oxidation. When things rust they use up oxygen. Combustion - There are three things needed for fire: oxygen, fuel, and heat. Without oxygen you can't have a fire. When things burn, they use up oxygen and replace it with carbon dioxide. PHOTOCHEMICAL REACTION IN THE ATMOSPHERE Photochemical reaction is a chemical reaction initiated by the absorption of energy in the form of light. The upper atmosphere forms outer defense against radiation and high energy particles that continuously bombard the Earth. These causes to two chemical changes: photodissociation and photoionization. Photodissociation is a chemical reaction that degrades compounds by bombarding the molecule with photons. Photodissociation of O2 formed atomic oxygen (O). Photoionization is when a molecule in the upper atmosphere absorbs solar radiation, it ejects an electron to form cation (Brown, et al., 2012). OZONE IN THE ATMOSPHERE Ozone shapes a sort of layer in the stratosphere, where it is more focused than anyplace else and this generally high fixation is referred to "ozone layer" or "ozone shield" Ozone and oxygen atoms in the stratosphere ingest bright light from the Sun, giving a shield that keeps this radiation from going to the Earth's surface. While both oxygen and ozone together absorb 95 to 99.9% of the Sun's ultraviolet radiation, only 137  College of Engineering Education 2nd Floor, BE Building Matina Campus, Davao City Telefax: (082)296-1084 Phone No.: (082)300-5456/300-0647 Local 133 ozone effectively absorbs the most energetic ultraviolet light, known as UV-C and UV- B. This ultraviolet light can cause biological damage like skin cancer, tissue damage to eyes and plant tissue damage. Acid Rain It is also called as Acid Deposition. It is any kind or form of precipitation that contains acidic components such as sulfuric acid or nitric acid that falls into the ground from the atmosphere (United States Environment Protection Agency, 2017). It is the result when sulfuric dioxide (SO2) and nitrogen oxides are released into the atmosphere. The SO2 and NOX react with water, oxygen, and other chemicals that is present in the atmosphere to form sulfuric and nitric acids. Small portions of the SO2 and NOX that cause acid rain is from that natural sources such as volcanoes but majority of it comes from the burning of fossil fuels in the industrial plants. The major sources of SO2 and NOX in the atmosphere are:  Burning of fossil fuels to generate electricity.  Vehicles and heavy equipments. and  Manufacturing, oil refineries and other industries.  SO2 and NOX can be blown by the winds over long distances and across borders, making it not only the problem of those people who live close to the source but for everyone in general.  Forms of Acid Deposition  Dry Deposition -A form of acid deposition. This is when gases and dust particles become acidic. The amount of acidity in the atmosphere that deposits to earth through dry deposition depends on the amount of rainfall an area receives.  Wet Deposition -Is what we commonly think of as acid rain. The sulfuric acid and nitric acids fall to the ground mixed in rain, snow, fog, or hail. 138  College of Engineering Education 2nd Floor, BE Building Matina Campus, Davao City Telefax: (082)296-1084 Phone No.: (082)300-5456/300-0647 Local 133  Measuring Acid Rain Ozone depletion According to the National Geographic (2009), the deteriorating of the ozone layer is due to the emission of pollution that contains Bromine (Br) and Chlorine (Cl). This deterioration allows large amount of ultraviolet (uv) B rays to reach Earth, which can cause harm to animals and skin cancer and cataracts in human. Chlorofluorocarbons (CFC’s) are the primary culprit of the ozone layer deterioration. When CFC’s reach the upper atmosphere, they are exposed to ultraviolet rays, which causes them to breakdown into substances. The chlorine in the CFC reacts with oxygen atoms in ozone and rips apart the ozone molecule. 139  College of Engineering Education 2nd Floor, BE Building Matina Campus, Davao City Telefax: (082)296-1084 Phone No.: (082)300-5456/300-0647 Local 133 The ozone layer, particularly the layer above the Antarctic has been impacted by the pollution since the mid-1980’s. About 90 percent of the CFC’s currently in the atmosphere were emitted by the industrialized countries in the Northern Hemisphere, including the United States and Europe. Self-Help: You can also refer to the sources below to help you further understand the lesson. Seinfeld, J. H., & Pandis, S. N. (2016). Atmospheric chemistry and physics : From air pollution to climate change. Retrieved from https://search.proquest.com/docview/2130891422/D95F6363E04B4AC6PQ/1 ?accountid=31259. Part I: The Atmosphere and Its Constituents pp 1-66 Casparian, A. S., & Sirokman, G. (2016). Applied chemistry for environmental engineering. Retrieved from https://search.proquest.com/docview/2131182488/10450024B2084AFBPQ/1? accountid=31259. Chapter 2: The Atmosphere and the Chemistry of Air pp 21-44 140