Water Chemistry

• High specific heat capacity


  • Water can absorb and retain heat without significant temperature changes
  • Crucial for regulating Earth's climate and maintaining stable temperatures in aquatic environments
• High heat of vaporization


  • Water requires substantial energy to transition from liquid to vapor
  • Cools surfaces (e.g., sweating) and helps moderate temperatures
• Density anomaly


  • Unlike most substances, water is denser in its liquid state than in its solid state
• Universal solvent


  • Water's polarity allows it to dissolve many substances
  • Essential for biological processes and the transport of nutrients
• Cohesion


  • Water molecules stick together due to hydrogen bonding
• Adhesion


  • Water adheres to other surfaces (e.g., plant capillary action)
• Surface tension


  • Water's cohesive forces create a "skin" on its surface
  • Insects can "walk" on water due to surface tension
• Capillary action


  • Water can climb up narrow tubes (e.g., plant roots, paper towels) against gravity
• pH neutrality


  • Pure water has a pH of 7 (neutral)
  • It can act as both an acid (donating H⁺ ions) and a base (accepting H⁺ ions)
• Transparency


  • Water is transparent to visible light
  • Allows sunlight to penetrate aquatic ecosystems
• pH of water from common sources

  • Rainwater (acidic)
  • Groundwater (alkaline)
  • Treated water (alkaline)
• Material that contributes to turbidity

  • Clay and silt particles
  • Algae and plankton
  • Dissolved colored organic compounds
  • Very tiny inorganic and organic matter
• Effects and importance of turbidity


  • Reduced light availability impacts aquatic ecosystems
  • Altered conditions for aquatic plants and animals
  • Cloudy water affects swimming and aesthetics
  • Sedimentation harms fish habitats
  • Turbidity provides attachment sites for pollutants like metals and bacteria
• Hard water


  • Water that forms when it percolates through deposits of limestone, chalk, or gypsum—minerals rich in calcium and magnesium compounds
  • These minerals dissolve in the water, leading to its hardness
• Water can dissociate into H+ (hydrogen) and OH- (hydoxide) ions through the process of autoionization.
• The pH scale is logarithmic, with each whole number representing a tenfold change in hydrogen ion concentration.
• A solution that has a pH less than 7 is acidic, while one greater than 7 is basic or alkaline.
• Lakes are bodies of freshwater surrounded by land and fed by streams and rivers.
• Bases are substances that accept hydrogen ions (H+).
• Acid rain can have negative effects on human health by causing respiratory problems and damaging buildings and monuments made of stone and marble.
• Acids have more free hydrogen ions than bases, which are substances with an excess of hydroxyl ions.
• Acid rain occurs when sulfur dioxide and nitrogen oxides from industrial processes react with oxygen molecules in the atmosphere to form acids such as sulfuric and nitric acid.
• Acids are substances that release hydrogen ions (H+), making them more reactive than other elements.
• A pH value of 7 indicates neutrality, while values below 7 indicate acidity and those above 7 indicate alkalinity.
• The pH scale measures hydrogen ion concentration on a logarithmic scale ranging from 0 to 14.