Our survival depends on the stability and conductivity of our surroundings. The environment and its resources are under constant stress due to the advancement of human society. Better and increased public knowledge is urgently needed, especially among the present and future generations. Chemistry is fundamental to all natural and artificial processes, & you need a clear foundation in the subject if you are to delve deeper into environmental science.
Assignments on environmental chemistry are an excellent way to boost ideas & knowledge and understand environmental pollution. However, completing these assignments requires a strong foundation in both chemistry & environmental science. Thousands look for chemistry homework help from reliable assignment help services.
Chemistry of Environmental Pollution
Unwanted solid or gaseous particles in the atmosphere cause tropospheric pollution. The main gaseous and particle contaminants found in the troposphere are as follows:
Gaseous air pollutants 🡪 These include hydrocarbons, ozone, hydrogen sulfide, oxides of sulfur, nitrogen, and carbon, and other oxidants.
Oxides of Sulphur: When sulfur contains fossil sulfur dioxide, a gas that is toxic to both plants and animals, sulfur dioxide oxides are created. It has been documented that very low levels of sulfur dioxide can bring on respiratory conditions such as asthma, bronchitis, and emphysema in humans. Sulfur dioxide irritates the eyes, causing them to water and become red. High SO2 concentration causes flower buds to become rigid and fall off plants. Sulfur dioxide oxidation without catalysis is a sluggish process. Nonetheless, the amount of particulate matter in the oxidation of sulfur dioxide to sulfur trioxide is catalyzed by contaminated air. 2SO2 (g) → 2SO3 (g) + O2 (g) Hydrogen peroxide and ozone can also be used to accelerate the reaction. (g) SO2 + (g) O3 → (g) SO3 + (g) O2 H2O2 (l) plus SO2 (g) yields H2SO4 (aq).
Oxides of Nitrogen: The two primary air components are dinitrogen and dioxygen. At room temperature, these gases don’t react with one another. When lightning hits at high altitudes, they mix to generate nitrogen oxides. After NO2 is oxidized, it produces NO3 nitrate ions, which are absorbed by the soil and act as fertilizer. When fossil fuel is burned in a vehicle engine at a high temperature, nitrogen and oxygen combine to produce sizable amounts of nitrogen dioxide (NO2) and nitric oxide (NO) as follows: N2 (g) plus O2. 1403K → 1403K TwoNO(g) In a millisecond, NO and oxygen combine to form NO2 2NO (g) + O2 (g) → 2NO2 (g). The rate at which NO2 is produced is higher when nitric oxide and ozone in the stratosphere interact. NO (g) -> O3 (g) + O2 (g) Nitrogen oxides are the cause of the annoying red haze in traffic and crowded areas. Elevated NO2 levels cause harm to plant leaves and slow down the process of photosynthesis. Children exposed to nitrogen dioxide may develop an acute respiratory illness due to lung irritation. It also poisons live tissues. Metals and certain textile fibers are harmed by nitrogen dioxide as well.
Particulate pollutants 🡪 are dust, mist, fumes, smoke, smog, etc.
Formation of photochemical smog 🡪 Numerous contaminants are released into the earth’s troposphere by burning fossil fuels. Nitric oxide (NO) and hydrocarbons (unburned fuels) are two contaminants released. When these pollutants accumulate to high enough concentrations, they interact with sunlight to cause a chain reaction that results in the conversion of NO into nitrogen dioxide (NO2). After absorbing solar energy, this NO2 splits into free oxygen atoms and nitric oxide (Fig. 14.2). N2 (g) (i) NO(g) + O(g) Because oxygen atoms are highly reactive, they react with airborne O2 to form ozone. O2 (g) plus O(g) O3 (g) (ii) The ozone produced by the reaction mentioned above (ii) quickly combines with the NO(g) created in reaction (i) to produce NO2 again. Brown gas NO2 can cause haze when its concentration is high enough. (iii) NO (g) + O3 (g) -> NO2 (g) + O2 (g) In addition to being potent oxidizers, NO2 and O3 can react with the unburned hydrocarbons in the contaminated air to produce compounds like formaldehyde, acrolein, and peroxyacetyl nitrate (PAN). Ozone is a hazardous gas. O + 3H2O -> 3CH2 = 3CH4 + 2O3. Phthaladehyde O=CHCH=CH2 Acrolein CH3COONO2 ｦ O Peroxyacetyl nitrate (PAN).
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