Evaporation vs. Boiling Article
What is Evaporation?
Evaporation is a process where liquid turn into vapor. Example is “water evaporated from the soil”
What is Boiling?
Boiling means rapid vaporization of any liquid. It happens when a liquid is heated to its boiling point. The boiling occurs in three different stages such as nucleate boiling, transition boiling and film boiling. There are no stages for evaporation.
Evaporation vs. Boiling
Boiling occurs when the temperature of the liquid is greater than the boiling point of the substance. Evaporation can occur at any temperature. It occurs as long as the substance remains liquid at a particular temperature.
According to Greg Bradburn, evaporation occurs when there is an increased energy present and occurs rapidly. It occurs from the bottom of the container when allowed to boil. The bubbles form at the bottom of the container and then rise on top of the container. In boiling, bubbles do not form at the bottom and rise to the surface. Evaporation occurs at room temperature and therefore, occurs at a slower rate when compared to boiling.
In boiling, there is formation of bubbles as it is a complex physical process and these bubbles are formed on a heated liquid. There is cavitation and acoustic effects can be seen as well.
There is no such bubbles formed in evaporation and there is no cavitation and acoustic effect present in evaporation.
The microscopic difference between evaporation and boiling is as follows:
In boiling, the motion of particles is increased and this force separates the particles apart from each other. The temperature is uniform and the boiling also occurs throughout.
In evaporation the movement of the particles is not the same. Few particles move at slower speed and few particles move at an higher speed. The surface particles are held in place by the particles beneath the surface layer and the particles in the middle layer is held by the forces acting on the sides of the container. The particles on the surface can break easily from the liquid.
| BOILING | EVAPORATION | |
|---|---|---|
| Definition of these two terms | Boiling is vaporisation of liquid into gas due to continuous heating. Most of the time it is not a natural process. | Evaporation on the other hand is a natural process and it is similar to boiling , but the liquid form changes into gaseous form when there is a increase in either temperature or pressure or both. |
| Occurrance | Large mass | only on surface |
| Amount temperature involved | Boiling happens when the temperature reaches to the boiling point. | In Evaporation the temperature does not need to reach to boiling point |
| Bubble Formation | Bubble formation is visible | Bubbles do not form in evaporation |
| Energy | Usually external source of energy is needed for boiling to happen. | Most of the time energy for evaporation is supplied by the atmosphere or surrounding. |
| Length of the process | Rapid Process | Slow process compared to boiling |
SUMMARY OF BOILING AND EVAPORATION:
1. Evaporation occurs on the surface of the liquid whereas boiling occurs at the entire length of liquid.
2. Boiling occurs rapidly whereas evaporation occurs slowly.
3. Evaporation occurs at any temperature whereas boiling occurs at a specific temperature.
4. The motion of particles is fast in boiling whereas in evaporation few particles move slowly and few at a faster rate.
5. There is formation of bubbles in boiling, but bubbles are not seen in evaporation.