Is evaporation a reversible physical change? Explain

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t-nez | High School Teacher | (Level 3) Associate Educator

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Evaporation is a reversible physical reaction. The reverse process is water condensing from the atmosphere onto a surface. Evaporation involves the change in state from liquid to gas. It's not the same as vaporization, or boiling, because it occurs at temperatures below the boiling point of the substance. Vaporization occurs at a substance's boiling point. 

Liquid in a closed container has some vapor above the liquid surface that's in equilibrium with the liquid. This means that the rate of evaporation equals the rate of condensation. When the container is open to the atmosphere the rate of evaporation usually exceeds the rate of condensation since equilibrium with the vapor in the atmosphere usually isn't reached. hoever, this isn't always true of water vapor. The atmosphere can become saturated with water vapor, meaning that equilibrium is established and no net evaporation will occur. The saturation point is temperature dependent. When the temperature drops after the atmosphere is at the saturation point condensation will occur, a reverse of evaporation. An example is dew forming on grass overnight.

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