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• Earth


  Blue planet
• Composition of earth


  • 70% water
  • 30% ground
• Composition of natural waters

  • 0.1% dissolved solids
  • 1000 ppm dissolved solids
• Earth


  Blue planet
• Composition of earth


  • 70% water
  • 30% ground
• Composition of natural waters

  • 0.1% dissolved solids
  • 1000 ppm dissolved solids
• Types of water


  • Freshwater (0-500 ppm dissolved solids)
  • Brackish (500-35,000 ppm dissolved solids)
  • Seawater (35,000 ppm dissolved solids)
• Seawater composition is 35 g of salt per 1 kg of water
• Water use


  Being depleted, limiting natural resource for economic growth
• Water use by countries

  • Developed countries
  • Developing countries
• Hydrological cycle

  System that describes the distribution and movement of water between the earth and the atmosphere
• Water on earth is continuously recycled through the hydrological cycle
• Water molecule

  • Forms 4 hydrogen bonds
  • Dipole
• Boiling point

  Temperature at which a liquid turns into a gas
• Melting point

  Temperature at which a solid turns into a liquid
• Heat of fusion

  Amount of heat required to convert 1g of solid to a liquid at its melting point
• Heat of vaporization

  Amount of heat required to convert 1g of liquid to vapor at its boiling point
• Acid-base properties of water

  Undergoes self-ionization and can act as both an acid and a base
• Temperature

  Density of water reaches a maximum at 4°C
• Heat capacity

  Quantity of heat required to raise the temperature of a given mass of a substance by 1°C
• Water has the highest heat capacity of all common liquids
• Water takes a lot of energy to heat up but once heated it holds the heat for a long time
• CO2 in water

  Most important weak acid, released by the decomposition of organic material by bacteria, dissolves from air into water
• Formation of acid rain

  1. SO2, NO3, CO2 react with water in the atmosphere

  2. Forming sulfurous acid, sulfuric acid, nitric acid
• Acid rain is a secondary pollutant, main source is coal burning plants
• Acid rain kills microorganisms, damages metals and limestone, kills fish, poisons plants
• Acid mine drainage is associated with mining of coal, rich in pyrite (FeS2)
• UAE is expecting a 50% increase in water demand, main source is agriculture, running out by 2030, water table dropping, increased salinity
• Water management and conservation

  1. Building dams

  2. Diversion

  3. Desalination

  4. Treating wastewater to potable water
• Drip irrigation

  Agricultural solution to water conservation
• Water pollution

  Change in water quality that can harm organisms or make water unfit for human use, causing illness, death, and disrupting ecosystems
• Types of water pollutants

  • Disease-causing agents
  • Oxygen-consuming wastes
  • Plant nutrients
  • Suspended solids and sediments
  • Dissolved solids
  • Thermal pollution
  • Oil pollution
  • Toxic materials
  • Radioactive substances
• Point source pollution

  Can be traced directly back to its source, single source
• Non-point source pollution

  Difficult to trace back to its original source, various sources
• Coliform bacteria count

  Used to determine if microorganisms are contaminating water
• Oxygen-consuming wastes deplete dissolved oxygen in rivers and lakes when released in water</b>
• 5 mg/L of dissolved oxygen is the level at which organisms start to be affected, 2 mg/L is hypoxia with severe effects on marine organisms, 0 mg/L is anoxia where only anaerobic organisms can survive
• Chemical oxygen demand (COD)

  Measure of the concentration of organic substances that can be oxidized by K2Cr2O7, not accurate as K2Cr2O7 may oxidize something other than oxygen-consuming waste
• Biochemical oxygen demand (BOD)

  Amount of oxygen required to break down or consume waste
• Dilution factor is used to find the BOD of an undiluted sample