Reducing the effects of Environmental Issues | Chemistry for Grade 11 (IGCSE) PDF Download

Reducing the Effects of Environmental Issues

• The impacts of climate change and acid rain are extensive, calling for strategies to mitigate their effects.

Dealing with Climate Change 

• To combat climate change, it is crucial to significantly reduce the production of greenhouse gases. This can be achieved by shifting to hydrogen and renewable energy sources like solar and wind power instead of relying on fossil fuels.
• By decreasing livestock farming, we can notably lower methane emissions arising from animal digestion.
• Increasing the number of trees planted can enhance the removal of carbon dioxide from the atmosphere.

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Dealing with Acid Rain

• Causes of Acid Rain: Acid rain occurs due to the presence of nitrogen oxides and sulfur dioxide in the atmosphere.
• Effects Reduction: To diminish the impact of acid rain, it is essential to lower the emissions of nitrogen oxides and sulfur dioxide.
• Role of Catalytic Converters: Catalytic converters installed in vehicles play a crucial role in eliminating nitrogen oxides from emissions.
• Reducing Sulfur Dioxide Emissions: There are two primary methods for reducing sulfur dioxide emissions:
  • Opting for low-sulfur fuels
  • Implementing flue gas desulfurization, a process involving the reaction of sulfur dioxide with calcium oxide to eliminate it from flue gas.

Oxides of Nitrogen in Car Engines

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Oxides of nitrogen

• Formation: Nitrogen and oxygen react in the high pressure and temperature conditions of internal combustion engines and blast furnaces to form NO and NO₂.
• Presence in Exhaust Gases: Exhaust gases also contain unburned hydrocarbons and carbon monoxide.
• Catalytic Converters: Cars are equipped with catalytic converters in their exhaust systems to neutralize these harmful exhaust gases.

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Catalytic Converters

• Composition: They consist of transition metal catalysts like platinum and rhodium.
• Structure: The catalysts are arranged in a honeycomb structure within the converter to maximize the reaction surface area.
• Redox Reactions: A series of redox reactions take place in the converter, neutralizing the pollutant gases.
• Carbon Monoxide Conversion: Carbon monoxide is converted to carbon dioxide through these reactions.
  2CO + O₂ → 2CO₂
• Oxides of nitrogen are reduced to N₂ gas:
  2NO → N₂ + O₂
  2NO₂ → N₂ + 2O₂
• A single reaction can summarize the reaction of nitrogen monoxide and carbon monoxide within a catalytic converter:
  2NO + 2CO → N₂ + 2CO₂
• Catalytic converters are designed to reduce the polluting gases produced in car exhausts:
  
• Unburned hydrocarbons can also be oxidized to carbon dioxide and water:
  C₈H₁₈ + 12½O₂ → 8CO₂ + 9H₂O