describe how intermolecular forces influence rates of vaporization, evaporation, and also condensation.

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On the roof that the residence in the photo below is a machine known together a "swamp cooler". This item of tools traces that origin back to the ancient Egyptians who hung wet blankets throughout the doors of your homes. Together the heat air passed v the blankets, water would certainly evaporate and also cool the air. The royalty went one action further and also had servants pan wet cloths over jugs the water to get an ext evaporation and also cooling.

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Figure (PageIndex1): A residence with a swamp cooler attached come the roof.

The beginning of the ax "swamp cooler" is not recognized - they absolutely don"t job-related in a swamp. Ideal conditions for cooling incorporate a high temperature (over (80^ exto extF)) and also a low humidity (preferably less than (30\%)). This coolers work well in desert areas, however don"t carry out any cooling in the humid areas of the country.


Evaporation

A pond of water left undisturbed ultimately disappears. The liquid molecules escape into the gas phase, ending up being water vapor. Vaporization is the process in i beg your pardon a liquid is converted to a gas. Evaporation is the counter of a liquid to that vapor below the cook temperature of the liquid. If the water is rather kept in a closed container, the water vapor molecules do not have actually a opportunity to escape right into the surroundings and also so the water level does no change. As part water molecules come to be vapor, one equal variety of water vapor molecules condense ago into the fluid state. Condensation is the change of state native a gas come a liquid.

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Figure (PageIndex2): Evaporation (A) and condensation (B).

In order for a liquid molecule to escape right into the gas state, the molecule have to have sufficient kinetic energy to get over the intermolecular attractive pressures in the liquid. Recall the a offered liquid sample will have molecules v a wide range of kinetic energies. Fluid molecules that have this certain threshold kinetic energy escape the surface and also become vapor. Together a result, the fluid molecules that remain now have actually lower kinetic energy. Together evaporation occurs, the temperature that the staying liquid decreases. You have actually observed the effects of evaporative cooling. On a warm day, the water molecules in her perspiration absorb human body heat and evaporate from the surface ar of your skin. The evaporating procedure leaves the continuing to be perspiration cooler, which in turn absorbs much more heat from your body.

A given liquid will evaporate an ext quickly once it is heated. This is due to the fact that the heating process results in a greater fraction of the liquid"s molecules having actually the vital kinetic energy to to escape the surface ar of the liquid. The figure below shows the kinetic energy distribution of fluid molecules at 2 temperatures. The numbers of molecules that have the required kinetic power to evaporate are presented in the shaded area under the curve at the right. The higher temperature liquid (left( T_2 ight)) has much more molecules that are capable of escaping into the vapor phase 보다 the lower temperature fluid (left( T_1 ight)).

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vaporize. In ~ this suggest the liquid begins to boil. The boiling point is the temperature at which the vapor pressure of a liquid is equal to the exterior pressure. The figure listed below illustrates the boiling of liquid.

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Figure (PageIndex4): Comparison between evaporation and boiling.

In the picture on the left, the liquid is below its cook point, yet some of the liquid evaporates. ~ above the right, the temperature has been enhanced until bubbles begin to type in the human body of the liquid. As soon as the vapor pressure inside the balloon is same to the outside atmospheric pressure, the bubbles increase to the surface of the liquid and burst. The temperature at which this process occurs is the boiling point of the liquid.

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The regular boiling suggest is the temperature in ~ which the vapor push of the liquid is equal to conventional pressure. Since atmospheric push can adjust based on location, the boiling suggest of a liquid alters with the exterior pressure. The common boiling suggest is a constant because the is characterized relative to the traditional atmospheric pressure of (760 : extmm : ceHg) (or (1 : extatm) or (101.3 : extkPa)).