What is Evaporation: Definition and 212 Discussions

Evaporation is a type of vaporization that occurs on the surface of a liquid as it changes into the gas phase. The surrounding gas must not be saturated with the evaporating substance. When the molecules of the liquid collide, they transfer energy to each other based on how they collide with each other. When a molecule near the surface absorbs enough energy to overcome the vapor pressure, it will escape and enter the surrounding air as a gas. When evaporation occurs, the energy removed from the vaporized liquid will reduce the temperature of the liquid, resulting in evaporative cooling.On average, only a fraction of the molecules in a liquid have enough heat energy to escape from the liquid. The evaporation will continue until an equilibrium is reached when the evaporation of the liquid is equal to its condensation. In an enclosed environment, a liquid will evaporate until the surrounding air is saturated.
Evaporation is an essential part of the water cycle. The sun (solar energy) drives evaporation of water from oceans, lakes, moisture in the soil, and other sources of water. In hydrology, evaporation and transpiration (which involves evaporation within plant stomata) are collectively termed evapotranspiration. Evaporation of water occurs when the surface of the liquid is exposed, allowing molecules to escape and form water vapor; this vapor can then rise up and form clouds. With sufficient energy, the liquid will turn into vapor.

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  1. G

    Solving Word Problems: Heat in a Cylinder & Evaporation of a Sphere

    my biggest problem is the word problems. i can't figure out how to write the equation so that i can do the math... Heat is escaping at a constant rate (dQ/dt is constant) through the walls of a long cylindrical pipe. Find the temperature T at a distance r from the axis of the cylinder if the...
  2. A

    Evaporation is a cooling process?

    A few days ago i took a test on heat and temperature ect. One of the questions was : When we say evaporation is a cooling process, we are saying that: a. surrounding air is cool b. the liquid is cooled. I chose a. because i knew that evaporation draws in energy from air to evaporate cooling the...
  3. T

    Evaporation Speed: Unit Measurement

    Does anyone know the most usual unit for evaporation speed? Is it kg/(m2*s)?
  4. 9

    How Does Ice Melt When Hot Water Is Added?

    Evaporation and Condensation... If 58 grams of hot water at 71°C is poured into a cavity in a very large block of ice at 0°C, what will be the final temperature of the water in the cavity? in °C How much ice must melt in order to cool the hot water down to this temperature? in grams is...
  5. marcus

    Quantum evaporation of a naked singularity

    this seems to be an interesting paper, though I can't tell for sure (don't understand the idea of naked singularity well enough, how you can have one) http://arxiv.org/abs/gr-qc/0506129 Quantum evaporation of a naked singularity Rituparno Goswami, Pankaj S. Joshi, Parampreet Singh 4...
  6. S

    Any takers approximating evaporation rate?

    Any takers approximating evaporation rate?! I am trying to estimate the rate of water loss from a 13'L x 6'W x 6'D mixing container at room temperature under a 12 inches of mercury vacuum. There is constant mixing of the fluid (dirty water). There is 180 cfm air movement through the top of...
  7. marcus

    Bojowald and Ashtekar: Black hole evaporation paradigm

    http://arxiv.org/abs/gr-qc/0504029 Black hole evaporation: A paradigm Abhay Ashtekar, Martin Bojowald 18 pages, 4 figures IGPG04/8-4, AEI-2004-072 "A paradigm describing black hole evaporation in non-perturbative quantum gravity is developed by combining two sets of detailed results...
  8. N

    Hawking radiation and BH evaporation time

    I don't know a lot about this topic so corrections are solicited. My understanding is that black holes evaporate by Hawking radiation. Hawking radiation, by my reading, occurs when a pair of virtual particles emerges very close to but just outside the event horizon of the black hole. When...
  9. T

    Do pH levels carry on thorugh evaporation?

    I need to know: In a closed system sealed off from outside air, if water from a mass of basic water evaporates, will the pH of the air be affected? If so, when the air condenses, how wil the pH of soil in the closed system be affected? Thanks for the help.
  10. F

    Creating a Large NaCl Crystal: Exploring Evaporation Techniques

    How would someone go about creating a large NaCl crystal? Is there a special evaporation technique involved with a saturated solution? As a side question why is sugar in crystal form? I mean isn't sugar a covalently bonded molecule?
  11. A

    What factors affect the evaporation speed of liquids?

    I'd like to know if there's any law/formula that allows you to calculate the evaporation speed of a liquid at a precise temperature, pressure, with a precise surface. Which physical parameters of the substance should i know? Thank You! Ciao! Andrea
  12. D

    Factors involved in water evaporation?

    Does anyone know the formula that describes the evaporation rate of water? I'm assuming it involves temperature, dew point, relative humidity and other factors. Thanks in advance.
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