The topic of “Environmental Chemistry” encompasses a broad range of topics, from pollution and its effects to strategies for its mitigation. Environmental chemistry includes all-natural elements in nature like water, soil, and air, and the factors affecting them and causing pollution and the ways to reduce it.
- Tropospheric Pollution:
- Oxides of Sulphur and Nitrogen:
SO2 +O2 →2SO3 (Formation of SO3 from SO2)
2NO+O2 →2NO2 (Formation of nitrogen dioxide)
2C+O2 →2CO (Formation of carbon monoxide)
3O2 →2O3 (In the presence of UV light)
CH4 +2O2 →CO2 +2H2O (Combustion of methane)
- Stratospheric Pollution: Depletion of zone layer due to chlorofluorocarbons (CFCs):
CFCl3 + UV → CFCl2 +Cl
2Cl + O3 → ClO + O2
ClO + O→ Cl + O2
- Hard Water: Causes of hardness include dissolved calcium and magnesium ions.
Ca(HCO3)2 → CaCO3 + CO2 + H2O (Calcium bicarbonate forming calcium carbonate)
- Eutrophication: Caused by excess nutrients like phosphates and nitrates leading to excessive growth of algae.
− NO2− + Bacteria → NO3 − (Nitrite being converted to nitrate)
Pesticides: Example: DDT (Dichlorodiphenyltrichloroethane)
Also Read : Avogadros Law
Metals and Non-metals:
Example: Hg, Pb, Cd, As and their harmful compounds like HgS, Pb(CH3COO)2, CdS, As2O3
Dyes, Drugs, and Detergents causing water pollution.
Also Read: Nucleophile Formula
Strategies to Control Environmental Pollution
2CO + 2NO → N2 + 2CO2 (Reduction of nitrogen oxide by carbon monoxide)
2C8H18 + 25O2 → 16CO2 + 18H2O (Combustion of octane)
Primary Treatment: Physical removal of large impurities.
Secondary Treatment: Biological treatment to remove organic matter.
Tertiary Treatment: Chemical treatment to make the water safe for discharge.
Acid Rain: Acid rain is caused by the release of sulfur dioxide (SO₂) and nitrogen oxides (NOₓ) into the atmosphere. These gases react with water vapor and other chemicals in the atmosphere to produce acidic solutions, which then fall as acid rain.
Sulphur Dioxide: Combustion of fossil fuels containing sulphur impurities:
SO2 + H2O → H2SO3 (Formation of sulfurous acid)
Nitrogen Oxides: Due to vehicular exhaust and industrial processes:
N2 +O2 →2NO2
2NO + O2 → 2NO2
NO2 + H2O → HNO3 + NO (Formation of nitric acid)
Effects: CaCO3 +H2SO4 → CaSO4 + H2O + CO2 (Limestone reacting with sulfuric acid)
Also Check – Bond Order Formula
Green Chemistry in Day-to-Day Life
Green chemistry, also known as sustainable chemistry, aims to design products and processes that minimize the use and generation of hazardous substances. It plays a role in daily life in numerous ways:
- Biodegradable Plastics: Made from plant-based materials such as cornstarch or sugarcane, reducing dependence on petroleum-based plastics.
- Natural Dyes: Used in textiles, replacing synthetic dyes that can be harmful.
- Non-Toxic Cleaning Agents: Many cleaning agents use natural substances like citric acid, vinegar, or baking soda, replacing harmful chemicals.
- Fuel Additives: Ethanol, which is often mixed with gasoline in many countries, is a renewable fuel produced from plants.
- Ethanol: C2H5OH
- Combustion of ethanol: C2H5OH + 3O2 → 2CO2 + 3H2O
- Solar Panels: Convert sunlight to electricity, reducing the need for fossil fuels. The primary reaction in photovoltaic cells involves semiconductors like silicon.
- Energy-efficient Appliances: Designed to operate using less energy, thereby reducing the overall environmental impact.
Environmental Chemistry Formula FAQs
Q1. What is environmental chemistry?
Ans. Study of chemical processes in the environment.
Q2. Why is the ozone layer important?
Ans. Protects from harmful UV radiation.
Q3. What causes acid rain?
Ans. SO₂ and NOₓ emissions reacting with water.
Q4. How does the greenhouse effect work?
Ans. Gases trap heat in Earth's atmosphere.
Q5. What are POPs?
Ans. Persistent Organic Pollutants; resist degradation.