Difference Between Sublimation and Evaporation

Main Difference

The main difference between sublimation and evaporation is that sublimation is the conversion of matter from a solid phase to the gaseous phase, whereas evaporation is the conversion of the liquid phase into the gaseous phase.

Sublimation vs. Evaporation

Sublimation is the conversion of matter from a solid phase to the gaseous phase without passing through the liquid phase, whereas evaporation is the conversion of the liquid phase into the gaseous phase. Solid-phase is the initial phase for sublimation while the liquid phase is the initial phase for evaporation. In sublimation, the enthalpy gives the amount of energy that is required for sublimation to occur; on the other hand, in evaporation, the enthalpy gives the amount of energy that is required for evaporation to occur. Sublimation changes its phase from solid to liquid without entering into a liquid state; on the flip side, evaporation changes its phase from liquid to gaseous state. Sublimation occurs at pressure and temperature below the triple point of a substance; conversely, evaporation happens on the surface of the liquid.

Comparison Chart

SublimationEvaporation
Sublimation is the conversion of matter from a solid phase to the gaseous phase without passing through the liquid phase.Evaporation is the conversion of the liquid phase into the gaseous phase.
Initial Phase
Solid-phase is the initial phaseLiquid phase is the initial phase
Enthalpy
Enthalpy gives the amount of energy that is required for sublimation to occurEnthalpy gives the amount of energy that is required for evaporation to occur
Phase Change
From solid to liquid without entering into a liquid stateLiquid to a gaseous state.
Occurrence
Occurs att pressure and temperature below the triple point of a substanceOccurs on the surface of the liquid

What is Sublimation?

Sublimation is the conversion of matter from a solid phase to the gaseous phase without passing through the liquid phase. In this, the solid directly changes into a gas. Sublimation is an endothermic reaction. From the time when chemical bonds between molecules should be broken down to release energy into the air, the energy should be given to break the. That’s why it is an endothermic reaction, and this energy is calculated as the enthalpy of sublimation. Sublimation occurs at pressure and temperature below the triple point of a substance. The triple pint of a substance is the pressure and temperature in which the substance exists in all three phases, i.e. solid, liquid, and gaseous phase. Below the triple point, solid water transfers, changing directly into the gaseous phase with a temperature increase, and never passing through the liquid state. Sublimation technique is used by chemists to purify compounds. A solid is generally placed in a sublimation apparatus and then heated under vacuum. The solid condenses and volatilizes as a purified compound on a cooled surface under this reduced pressure and leaving behind a non-volatile residue of impurities. Once the heating stops and the vacuum is removed, the purified compound then may be collected from the cooling surface.

Examples

  • Water: Turning of dry ice into gaseous carbon dioxide at room pressure and temperature.
  • Naphthalene: An organic compound that easily sublimes at standard pressure and temperature is naphthalene.
  • Other Substances: Iodine produce smokes on gentle heating and possible to obtain liquid iodine by controlling the temperature at just above the melting point of iodine at atmospheric pressure.

What is Evaporation?

Evaporation is the conversion of the liquid phase into the gaseous phase. Evaporation is also an endothermic process, and intermolecular forces between molecules of liquid should be broken down to form its vapor. So this reaction requires energy to break the bonds. Hence, it is an endothermic reaction. Evaporation is the opposite reaction of condensation. It is directly related to the temperature because when the temperature is increased, the rate of evaporation is also increased. Evaporation occurs on the surface of the liquid. The molecules in the mid or bottom of the liquid have a high amount of intermolecular forces compared to the molecules near the surface of the liquid. Therefore, the molecules on the surface of the liquid can be easily released and also these molecules are the first to be converted into the gaseous phase.

Factors Affecting the Rate of Evaporation

  • The Concentration of Substance in Air: If there is a high quantity of evaporating substance in air, then the process of evaporation occurs gradually.
  • The Flow Rate of Air: A higher rate of airflow increases the evaporation.
  • Intermolecular Forces: The enthalpy of evaporation is high if the intermolecular forces are stronger, then the evaporation is slow.
  • Surface Area: An area with a large surface is helpful for higher evaporation.

Key Differences

  1. Sublimation is the conversion of matter from a solid phase to the gaseous phase without passing through the liquid phase, whereas evaporation is the conversion of the liquid phase into the gaseous phase.
  2. Solid-phase is the initial phase for sublimation while the liquid phase is the initial phase for evaporation.
  3. In sublimation, the enthalpy gives the amount of energy that is required for sublimation to occur; on the other hand, in evaporation, the enthalpy gives the amount of energy that is required for evaporation to occur.
  4. Sublimation changes its phase from solid to liquid without entering into a liquid state; on the flip side, evaporation changes its phase from liquid to gaseous state.
  5. Sublimation occurs at pressure and temperature below the triple point of a substance; conversely, evaporation occurs on the surface of the liquid.

Conclusion

Above discussion concludes that sublimation is the conversion of matter from a solid phase to gaseous phase without entering into the liquid phase, whereas evaporation is the conversion of the liquid phase into the gaseous phase.

Harlon Moss

Harlon currently works as a quality moderator and content writer for Difference Wiki. He graduated from the University of California in 2010 with a degree in Computer Science. Follow him on Twitter @HarlonMoss

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