Chemistry

Difference between Evaporation and Boiling

The Main Difference between Evaporation and Boiling is that evaporation is a type of phase transition which occurs on the surface of a liquid as it changes into the gas phase. it happens when water is heated up. evaporation always occurs at a fixed temperature and takes place throughout the liquid. while Boiling is the rapid vaporization of a liquid that occurs when a liquid is heated to its boiling point. it is the temperature at which the vapor pressure of the liquid is equal to the pressure exerted on the liquid by the surrounding. it can occur at any temperature. boiling is a slow process than evaporation.

Difference between Evaporation and Boiling in tabular Form

Evaporation Boiling
Evaporation occurs when the phase change happened. i.e. from liquid to gas. it increases the temperature or pressure of liquids and is a relatively slow and natural process. it is an unnatural process and is caused when liquids are heated under high temperature and until heating of liquids continues.
in this process, the temperature does not necessarily reach a boiling point. The boiling process occurs when the temperature reaches equal to the boiling point.
it occurs on the surface of the liquid when they are heated. it occurs on the entire mass of liquid on heating them at high temperature.
Energy is gained usually from the atmosphere or surroundings. boiling has occurred with the help of some external energy source.
bubbles are not so much visible in this process. the boiling process is caused by bubbles in liquids at a large scale.
evaporation is a bit slower process as compared to boiling. in contrast, it is faster and quicker than also carried rapidly.
evaporation can takes place below the temperature of boiling point. the boiling point starts when the temperature of the liquid rises than the temperature at which evaporation takes place.
the temperature may change. the temperature remains constant.

What is Evaporation?

the transitional process of a substance from liquid to gaseous state is known as evaporation. it always occurs at the surface or vapor level. also, it is a reverse process of condensation ( a process of transition from vapor to liquid). when both liquids during evaporation and solid body are cooled by reducing the temperature, energy is released and molecules are evolved.

In most cases, evaporation of liquids is carried out by providing sufficient heat but in some cases, decreasing pressure will also consequence to proceed directly in a gaseous state. this process is known as sublimation.

characteristics of Evaporation | Difference between Evaporation and Boiling

when evaporation takes place in solids, it is called sublimation while in liquids is known as vaporization. vaporization at the free surface of liquid results in thermal motion of molecules at below boiling point temperature. in this situation, the pressure of the gaseous medium on the specified surface is present normally. as a result, kinetic energy is pulled from the upper layer of liquid in the gaseous state.

in this process, some molecules are bounced back or reflected towards the liquid state and hence are captured by liquid.

What is Boiling?

the transition of phase from liquid to a gaseous state is known as boiling. during this process, heat is transferred to the liquid to equal or higher than the liquid’s boiling point at a given pressure. the boiling is carried out with different methods, and mechanisms from which two major mechanisms are as follows:

  • boiling in a stream or convective boiling.
  • boiling in large volume.

when the temperature of liquids rises water molecules start to evaporate in the form of bubbles with increasing their sizes. on reaching a specified size, the molecules or bubbles are starting to detach from the surface of the liquid. if water is kept not so much hot, the vapor bubbles cold layer collapse.

on the other hand, providing sufficient temperature, the water molecules reach the surface of the liquids and burst by leaving steam. on this spot, we can hear a clear noise while proceeding boil.

The boiling point of a liquid mainly depends on two factors:

  • from the kind of liquid
  • from external pressure

Each substance has its own boiling point

boiling point of different substances

if we decrease the pressure of liquids, air bubbles start floating easily and hence boiling occurs even at low temperatures. this is the reason that at high mountains at 6000 – 8000m heights, we have consequences hurdles to cook food, soup or any other meat. here, we use readymade canned foods instead of cooking. at this stage, the boiling point of water decreases from 100° C.

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