(CHEM) L3 Properties of Liquids and IMFs

• Surface Tension

  • Refers to the force that causes the molecules on the surface of a liquid to be pushed together and form a layer.
  • The surface molecules lock into a thin layer of elastic membrane because they are all attracted with each other and are being pulled by the molecules at the center.
• Viscosity

  • The resistance of fluids to flow.
  • A substance that flows readily has low viscosity.
  • A measure of the substance’s intermolecular force of attraction (IMFA).
  • If the IMFA is strong, the liquid will have a high viscosity because it will have a high resistance against flowing.
• Vapor Pressure

  • The pressure of the vapor resulting from evaporation of a liquid above a sample of the liquid in a closed container.
  • If a liquid has weak intermolecular forces of attraction, the escaping tendency of the molecules is high.
• Boiling Point

  • The temperature at which the vapor pressure of the liquid is equal to the atmospheric pressure.
  • Liquids that have high vapor pressure have low boiling points.
• Molar Heat of Vaporization

  • The amount of heat needed to vaporize a given amount of substance as its boiling point.
• Properties of Liquid

  • Viscosity
  • vapor pressure
  • Boiling point
  • Surface tension
  • Molar heat of vaporization
• Properties of Water

  1. It has high boiling point
  2. It has high specific heat
  3. It has high heat of vaporization
  4. It has high surface tension
  5. It is the only substance that contracts when cooled
• Heat of Vaporization

  Heat energy needed for vaporization.

  HOV of Water 540cal/g
• Specific Heat


  Measurement of heat that is needed to be absorbed/loss for 1g of a substance to increase in temperature by 1°C

  4.186 J of Heat to increase the temperature of water by 1°C
• Evaporative Cooling


  Cooling down in living organisms