Evaporation Causes Cooling

Introduction

Evaporation causes cooling which is based on evaporation of a liquid from any surface leaving a cooling effect. The degree of cooling effect are left by the evaporating liquid can vary based on the liquid. It is exemplified by evaporating alcohol or water that leaves a cooling effect on the surface.

The variation in degree of cooling is also very clear between alcohol and water. Where, alcohol has a higher degree of evaporation of cooling effect than water. This variation depends on the nature of molecules of the liquid.

What is Evaporation?

A very common definition for evaporation is the process of conversion of a liquid into vapour is called evaporation.

Figure 1: Process of Evaporation

Any liquid or solid being converted into vapour form results in evaporation and simultaneously a cooling effect is felt. The best example to understand cooling through evaporation is spraying perfume and experiencing cold feeling. This signifies the transformation of the liquid from the perfume bottle to vapour during spraying it. One can only differentiate the degree of cold experienced in different liquids while evaporating.

Evaporation causes Cooling

Evaporation causes cooling can be understood by the cooling effect on water on earthen pots. It can be observed the temperature of stored water in earthen pots is lower than the room temperature. The primary reason for cool water in earthen pots is the seeping of water through its microscopic pores. The evaporating water through pores absorbs the heat inside the pot resulting in water cooling.

Figure 2: Cooling as a result of Evaporation

This cool water helps to keep refresh in the summer season. As the rate of evaporation is affected by temperature, the cooling of water slows down during rains and speeds up during summers.

Factors affecting the rate of Evaporation

Every other natural phenomenon is affected by different factors. The rate usually is determined by the role of these factors. Similarly, there are factors affecting the rate of evaporation. These are as follows −

Figure 3: Factors affecting Rate of Evaporation

Temperature

Temperature (around the substance) is a factor that stands directly proportional to the rate of evaporation. With the increase in temperature the rate of evaporation also increases and vice-versa.

Atmosphere's Humidity

The evaporation rate stands inversely proportional to the humidity of the atmosphere around. This means lower the humidity higher is the rate of evaporation.

Surface Area

Evaporation is a surface phenomenon. Evaporation rate increases with the increase in surface area of the given liquid. Therefore, more the surface area more is the rate of evaporation.

Force of Attraction (Intermolecular)

Intermolecular forces become a very important factor among deciding factor for evaporation to take place. Rate of evaporation or even the very initiation of evaporation is determined by the intermolecular forces of attraction. The forces are different for different liquids. More the forces between molecules, lesser are the chances of evaporation.

Wind's Speed

The speed of wind is directly proportional to the evaporation rate. This is exemplified by quick drying of clothes witnessed on a windy day.

Evaporation: Application

Some of the common and overlooked applications of cooling effect of evaporation are as follows −

• Cotton clothing worn in summers. It is to let the clothes absorb water in the form of sweat. This leads to them acting as a coolant or cooler themselves.

• Drying and concentrating samples for laboratory purposes is another application of evaporative cooling. This is usually used in chromatography and spectroscopy.

• Matki, a traditional container in Indian households, also works on the principle that evaporation causes cooling.

• Air conditioners based on evaporative cooling provide cool air by blowing air through a filter soaked in water.

• Sweating, a natural phenomenon based on sweat evaporating offs the body, leaving a cooling effect.

Evaporation Causes Cooling: Advantages and Disadvantages

Advantages

The advantages related to evaporation causes cooling are as follows −

• It is the ideal situation for cooling in a dry climate. The lower humidity in the air (dry air) propagates the rate of evaporation thus cooling effect is increased.

• An evaporative cooler when used can also be effective in filtering out the allergens, dust particles, and pollens in the air.

• Evaporative cooling can be a method of enjoying convenience with managing health and avoiding any harm to nature.

• Using evaporative cooling helps you reduce energy wastage by 80%.

Disadvantages

The disadvantages accompany the phenomenon of evaporation causes cooling are as follows −

• Evaporative cooling is a risky choice for high humidity areas. This makes this less desirable in comparison to air conditioners not using this phenomenon as its core.

• It heightened humidity due to the evaporative cooling impacts a negative sign. It promotes growth of mildew, dust mites etc. This plays a role in triggering asthma and various different allergic complications.

Conclusion

The phenomenon of evaporation causing cooling is a property of any liquid. The liquid evaporates after absorbing energy in the form of heat. The heat absorbed helps in evaporating the water molecule in slow rate and makes thee environment cool as heat has been absorbed by the water molecules.

This is how evaporation causes cooling. This phenomenon is applied in various daily needs. Clothing, appliances, etc. are some very common examples of applications of evaporation causing cooling in daily needs.

FAQs

Q1. What is condensation?

Ans. Condensation can simply be defined as a process opposite to evaporation. Condensation undergoes loss of heat and the vapours of water turn into droplets of water. This process is called condensation.

Q2. Is evaporation an endothermic or exothermic process?

Ans. As evaporation includes absorption of heat, it is an endothermic process.

Q3. In context with evaporation, what does surface phenomenon mean?

Ans. When the surface molecules of any liquid convert into gas it results in evaporation. This makes evaporation a surface phenomenon because surface molecules are involved.

Q4. What is the role of evaporation causes cooling in cooling down a room's temperature?

Ans. The water on being pumped in the machine pushes out or forces our air through the outlet. This air is cooler because the water absorbs the heat. This causes cooling down of the room temperature. This water on absorbing heat finally evaporates as water vapour.