HSC Chemistry: Need For Monitoring The Environment


This is part of the HSC Chemistry course under the topic Analysis of Inorganic Compounds. 

HSC Chemistry Syllabus

  • analyse the need for monitoring the environment

Why Do We Need to Monitor The Environment?

This video in particular will be exploring why there is a need to monitor the environment, as well as providing some brief information on the environmental implications of different forms of oxides. This video explores the following substances:

  • Oxides of carbon
  • Oxides of nitrogen
  • Oxides of sulfur
  • Phosphorus
  • Heavy metals e.g. lead and mercury
  • Calcium and magnesium ions in hard water


Environmental Monitoring Analysis

Air Quality Monitoring

  • Oxides of carbon
    • Complete combustion produces carbon dioxide while incomplete combustion produces carbon monoxide and soot.
    • Carbon dioxide is greenhouse gas that contributes to global warming and decrease in ocean’s pH due to its acidic nature.
    • Carbon monoxide is odourless, toxic as it interferes with the blood’s ability to transport oxygen throughout the body.
    • Soot causes cancer
  • Oxides of sulfur
    • Sulfur dioxide is produced from the burning of fossil fuels. SO2 causes irreversible respiratory problems and formation of acid rain (reduction in ocean’s pH). 
  • Oxides of nitrogen
    • Nitrogen dioxide is broken into free radicals when exposed to sunlight (UV light). These reactive radical species can react with hydrocarbons and oxygen in the air to form ozone – photochemical smog. The smog decreases visibility.
    • Nitrogen dioxide also contributes to the formation of acid rain:
  • Haloalkanes
    • Haloalkanes, if not processed appropriately, can reach Earth’s atmosphere to generate free radicals. These free radicals in turn react with the ozone (O3), leading to its depletion.

Soil quality monitoring

  • Essential nutrients such as carbon, nitrogen and phosphorus are cycled and stored in soil


Water quality monitoring

  • Agricultural use
    • Phosphate ions occur in natural waterways e.g. rivers at low concentrations and are essential for the growth of aquatic plants. However, excessive phosphate levels will promote algal growth (‘bloom’), negatively impacting the ecosystem.
  • Hardness – calcium and magnesium ions
  • Heavy metals
    • Lead (Pb2+) and mercury ions (Hg2+) are toxic to humans (brain-associated effects).
    • Pb2+ ions can originate from lead-based pigments (e.g. paint) and fuels
    • Hg2+ ions can originate from chemical factories and medical devices (e.g. thermometer)
  • pH
    • Monitoring H+ ions are essential for maintaining aquatic ecosystems e.g. fish, coral reef