Evaporation

Examples of Evaporation in the following topics:

• Liquid to Gas Phase Transition

  • There are two types of vaporization: evaporation and boiling.
  • Evaporation occurs at temperatures below the boiling point, and occurs on the liquid's surface.
  • If the vapor pressure of the drop is greater than the partial pressure of vapor in the gas phase, the drop will evaporate.
  • Non-polar molecules (gray) evaporate or boil more quickly than polar molecules (blue and red).
  • This video looks at how vaporization and evaporation happens, and it addresses a big mistake that many people make when they deal with the liquid gas phase transition.

• Vapor Pressure of Nonelectrolyte Solutions

  • A substance that evaporates quickly has high vapor pressure and is referred to as a volatile substance.
  • By definition, a non-volatile substance does not evaporate.
  • In a pure solvent, all of the liquid molecules on the surface can evaporate and transition to the gaseous phase.

• Solid to Gas Phase Transition

  • For some substances, such as carbon and arsenic, sublimation is much easier than evaporation.
  • Even ice has a measurable vapor pressure near its freezing point, as evidenced by the tendency of snow to evaporate in cold dry weather.

• Boiling Point Elevation

  • The lower number of solvent molecules at the surface means that fewer will evaporate, and thus the vapor pressure is lowered.

• Millikan's Oil Drop Experiment

  • Ordinary oil would evaporate under the heat of the light source, causing the mass of the oil drop to change over the course of the experiment.

• Properties of Nitrogen

  • Directing a pressurized stream of nitrogen gas perpendicular to the surface of the liquid allows the solvent to evaporate while leaving the solute(s) and unevaporated solvent behind.

• Properties of Phosphorus

  • Another form, scarlet phosphorus, is obtained by allowing a solution of white phosphorus in carbon disulfide to evaporate in sunlight.

• Three States of Matter

  • This process of a liquid changing to a gas is called evaporation.

• Molecular Crystals

  • Molecular solids tend to be soft or deformable, have low melting points, and are often sufficiently volatile to evaporate directly into the gas phase.