CHEM12

• Water


  An inorganic compound that is colorless, odorless, tasteless, but it is considered as the most important compound in the body
• 50% of water or more is in the normal adult's body
• Water


  The capability of dissolving more substances than any other liquid made it as "universal solvent"
• Main properties of water

  • Polarity
  • Cohesion
  • Adhesion
  • Surface tension
  • High specific heat
• Molecular structure of water

  • One oxygen atom covalently bonded with two hydrogen atoms
  • Sharing of electrons from the outer energy shell of two atoms of oxygen makes covalent bond
  • Sharing of these electrons is not shared equally within the molecule making it polar
• Hydrogen bond


  The bond that holds each water molecule with the adjacent water molecule
• Hydrogen bond makes the water polar and explains why water is a universal solvent
• Specific heat


  The amount of heat needed to raise the temperature of 1 gram of a substance 1 degree Celsius (°C)
• Water has a high specific heat because an amount of energy is needed to break the hydrogen bonds between water molecules
• At temperatures below 4°C, the density of water did not increase but rather decreased
• Anomalous expansion of water


  The behaviour where water expands instead of contracting when the temperature goes from 4°C to 0°C, and it becomes less dense because water molecules normally form open crystal structure when in solid form
• The anomalous expansion of water supports the marine life in the colder regions where the formation of ice on bodies of water is evident
• Surface tension


  The highest cohesion of any non-metallic liquid, due to the hydrogen bonding in water molecules
• Surface tension of water


  • Presence of droplets on the surface of leaves or some paper wax where the water beads up
• Water has the highest heat of vaporization and vapor pressure among non-metallic liquids
• The properties of water make it the most important compound in the body