Question

what is evaporation & discuss in detail the factor affecting evaporation ?

Answer 1

Evaporation is the process by which water changes from a liquid state to a gaseous or vapor state .A substance that has a larger surface area will evaporate faster, as there are more surface molecules per unit of volume that are potentially able to escape. the higher the temperature of the substance the greater the kinetic energy of the molecules at its surface and therefore the faster the rate of their evaporation.

Answer 2

EVAPORATION :
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The phenomenon of change of liquid to the vapour state at any temperature below the boiling point of the liquid.

Some real life examples :
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» During summers, we get relief under a fan. Actually , the air from the fan causes quick Evaporation of sweat from our body. This needs energy which is taken from our body. The body temperature gets lowered and we get relief.

» A desert cooler is quite effective in summer. In fact , hot and dry air passes through the wet pads of wood - shavings. water present evaporates and in the process, the temperature inside the cooler gets lowered. That is why, the air from it is very cool. The fan inside the desert furthur speeds up the process of Evaporation of water.

» In summers, or on a hot sunny day , people generally sprinkle water on the roof or on the ground . As water evaporates , it takes up heat from the surface. As a result , cooling is caused . They sleep comfortably during the night.

» we prefer cotton clothes in summers , since cooling is caused during Evaporation the body temperature gets lowered . we feel more comfortable. cotton is porous nature and is good absorber of water coming out of the pores as sweat, as the sweat evaporates, it absorbs some energy from the body since the clothes are in contact with our skin. The temperature of the body gets lowered and we feel more comfortable.

FACTORS AFFECTING EVAPORATION :
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1.) Surface area available for Evaporation :

Evaporation is a surface phenomenon which means that only the particles or molecules of the liquid present on it's surface change into vapour. Thus, greater the surface area of the liquid more will be the rate or extent of Evaporation.

2.) Increase in temperature :

the Evaporation of water or any other liquid becomes fast if the atmospheric temperature is high or we can say that the Evaporation of a liquid is fast in summer as compared to winter. Actually, the increase in temperature also increases the kinetic energy of the particles or molecules of the liquid . They acquire greater tendency​ to change to the vapour state, as a result , the Evaporation becomes fast.

3.) Descreas in Humidity :

Humidity represents the amount of water vapours present in air. In case, the humidity level or amount of water vapours in air is already high, then the rate of Evaporation descreas.

4.) Increase in the speed of wind :

The speed of the wind around us has also some effect on Evaporation of the liquid. we often noticed that the wet clothes dry fast on a windy day. it is due to with the increase in wind speed , the particles of water vapours present in air also move away and the air which replaces it, is comparitively dry. This will enhance or increase the rate of Evaporation.

5.) Nature of the liquid :

Apart from these, another factors which is of great importance is the nature of the liquid which is evaporating . For example : alcohol evaporates at a faster rate than water, the boiling point of alcohol is 350k is less than that of water 373k , This means that interparticles forces of attraction in alcohol are less than in water. Therefore, alcohol will evaporate faster than water.

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