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As we know Evaporation can happen at any temperature but also to break the bonds, atoms need to have enough kinetic energy which when averaged in water equal to 100°C(boiling point). So what I am asking is that for evaporation to occur we need molecules(those will break their bonds) should at least be at 100°C in water. Not all molecules have to be at 100°C or the kinetic energy required to break the bonds but those who will should definitely be at 100°C. I want to confirm whether it's true or not.

Yes, temperature is average kinetic energy of whole matter but here by temperature I basically meant the kinetic energy of atom.

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  • $\begingroup$ If you're talking about Evaporation of water specifically, and even then the bonds holding water molecules to one another isn't a chemical bond, it's due to electromagnetic attraction from the water molecules being polar. $\endgroup$
    – Triatticus
    Commented Mar 13, 2021 at 16:18
  • $\begingroup$ Water molecules do not need to have a temperature of 100 deg C to leave the liquid state and evaporate. What you are describing is boiling water at 1 standard atmosphere. $\endgroup$ Commented Mar 13, 2021 at 16:45

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As we know Evaporation can happen at any temperature. But also to break the bonds atoms need to have enough kinetic energy which when averaged equal to 100°C. So what I am asking is that for evaporation to occur we need atoms(those will break their bonds) should at least be at 100°C.

In thermodynamics temperature is a macroscopic property. Kinetic temperature is the average translational kinetic energy of the atoms and molecules. Individual atoms and molecules don't have a temperature. But they can have translational kinetic energy above or below the average, per the Stephan-Boltzmann distribution. Those atoms and molecules having higher kinetic energy below the surface of the liquid are unable to escape the liquid.

On the other hand, those atoms and molecules having higher kinetic energy than the average at the surface of the liquid can escape into the air above the surface. When they do, they take their higher kinetic energy away from the other atoms and molecules at the surface, thereby lowering the average kinetic energy of the atoms and molecules (and temperature) at the surface. This phenomenon is known as "evaporative cooling".

Not all atoms are at 100°C or the kinetic energy required break the bonds but those who will should definitely be at 100°C. I want to confirm whether it's true or not.

Again, temperature is a macroscopic property. Individual atoms and molecules don't have a temperature.

Again, not all atoms and molecules of the liquid have kinetic energy equal to the average kinetic energy of all the atoms of the liquid, which equals the kinetic temperature of the liquid. Those atoms that have higher kinetic energy than the average at the surface of the liquid have the opportunity to escape the liquid.

Hope this helps.

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Yes, the kinetic energy of a molecule breaking from the liquid would be at least the average kinetic energy of a molecule of steam.

Evaporation lowers the average energy of the liquid by removing the molecules at the higher end of the energy distribution - this is known as Evaporative Cooling and it's how, among other things, sweat works.

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