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1800-102-2727Fill a beaker halfway with water. Place this beaker over the flame and continue to heat it. After a while, you'll see that the water starts to boil and turns into vapour. This is referred to as vaporisation. Have you ever noticed that if a glass of water spills on the floor and no one dries it up, will it dry after a while? Wet clothes dry after a while. Do you know how this happens? Because particles of matter are never at rest. They are always moving. They have various amounts of kinetic energy at different temperatures.
A small fraction of particles at the surface of a liquid, with higher kinetic energy, can break away from the forces of attraction of other particles and become vapours. Evaporation is the transformation of a liquid into vapour at any temperature below its boiling point.
The rate of evaporation is affected by the following factors:
1. Surface area: Evaporation is a surface phenomena, thus it takes up a lot of space. The rate of evaporation increases as the surface area increases. We spread our things out to dry them faster, for example.
2. Temperature - As the temperature rises, so does the rate of evaporation. As the temperature rises, a greater number of particles gain sufficient kinetic energy to enter the vapour state. Wet garments, for example, dry quickly in the sun.
3. Humidity - Refers to the amount of water vapour in the air. At any given temperature, air can only hold a certain amount of water vapour. The rate of evaporation slows down when the amount of water in the air is already high or at its maximum.
4. Wind Speed - As wind speed increases, water vapour particles travel away from the wind, reducing the amount of water vapour in the environment. As a result, as the wind speed increases, so does the rate of evaporation. On a windy day, for example, clothes dry faster.
Fill a beaker with water once more. Place this beaker over the flame and continue to heat it. After a while, you'll see that the water starts to boil and turns into vapour. Cover the beaker with a lid and turn off the heat. When you remove the lid after a minute, you will notice water droplets on one side of the lid. This is due to the fact that water vapour condenses and reverts to a liquid state. Condensation is the transition of a substance's physical state from gas to liquid. This is the vaporization process in reverse.
When you take a chilled soft drink bottle out of the fridge and set it aside after drinking, you'll notice little drops of liquid on the bottle's surface after some time. This is an example of condensation as well. It happens when warm air vapour collides with a cool surface and cools down to change its condition.
Water, like all other substances, is made up of atoms. Because these atoms are energetic, they move quickly. When these particles are in the form of vapour, they are far apart. As a result, when this vapour is exposed to cooler temperatures, the particles become less energetic and closer together. As a result, when vapour reaches a certain energy level, it transforms into liquid.
Evaporation | Condensation |
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Evaporation is the transformation of a liquid into vapour at any temperature below its boiling point. | Condensation is the transition of a substance's physical state from gas to liquid. |
The state of matter shifts from liquid to vapour during this process (gas). | The state of matter shifts from gas to liquid during this phase. |
The forces of attraction between particles get weaker during this process, which is why liquid turns into vapour. | The forces of attraction between particles become quite strong throughout this phase, which is why gas turns into liquid. |
It takes place at a low elevation. | It takes place at a low elevation. |
It takes place at a low elevation. | It's an exothermic reaction. |