why does water vaporise?
410101
Well if I were water I would want to vaporize. That is when my molcules get far apart because I was heated up. \n\nThe only other thing water can do is freeze. So I would want to vaporize.
642580
Vapors are the result of molecules of liquid escaping into the gas phase in the attempt to minimize the difference in chemical potenial between the liquid phase and the gas phase.  Where there is not liquid phase, there is no vapor, only gas.  \n\nExample:  water at room temperature is a liquid with a vapor pressure (caused by water molecules escaping from the liquid into the gas phase).  Oxygen, on the other hand, does not exist in the liquid phase at room temperature and is referred to as a gas.  If one condenses oxygen to the liquid phase, there would be a vapor pressure of oxygen in the gas phase above the liquid and these gas phase molecules would be referred to a "vapor".
95618
basically you're talking about distilling water, which is a purification technique.  collect the water vapor and let it condense. the result is pure water.
1047674
Intermolecular forces (vander waals, hydrogen bonds), are very much weaker than covalent or ionic bonds\nyou see, when we evaporate water in its boiling points(or other liquid), we break the intermolecular forces (in water's case, hydrogen bonds), but the heat still cannot break up covalent H-O bonds, so the chemical formula of water vapour is still H2O but with no intermolecular forces
902589
Wow. There are a lot of bad answers here. For a given mass, steam will have more energy than water. The difference is called the 'heat of vaporization'. One thing to be carefuls about, of course, is that a given mass of steam will occupy much more volume than the same mass of water.
577442
The water vapor which is released through the combustion of the gases becomes like fog and converts to water droplets when cooled in the air. This is just like the clouds
652151
Gas molecules are dissolved to a certain extent depending on the intermolecular interactions with the gas molecule with the water molecules (for example), evaporation occurs at the surface of the liquid, and this is where the gas molecule, if given enough kinetic energy, can break apart from the water molecules.  With the increase in temperature, the average kinetic energy of the gas molecules and that of water becomes greater, and they can both escape with greater kinetic energies.\n\nhttp://www.freewebs.com/chemistryhomework
579734
Water always evaporates. Higher temperatures will increase the evaporation rate, but water always evaporates. It has no relation with the boiling point; evaporation is a different phenomenon.\n\nExtracted from wikipedia:\n"It is a misconception that at 1 atm, water vapor only exists at 100 °C. Water molecules are in a constant state of evaporation and condensation flux near the surface of liquid water. "
985521
Your body absorbs the vapour like a sponge...:D
420369
CONDENSATION, it's the same way we get rain!  water evaporates from heat, it turns into vapor(clouds) and when they get enough water, it rains!
751012
Clouds are formed essentially by water vapours.The uppermost layer of waterbodies like sea,river,ponds etc(specially sea) are in the process of evaporation always.now water vapour is a gas and due to the fa that the surface of the waterbodies and the earth is hotter,the watervapour expands its volume.As you must be knowing density of an object is its mass divided by volume.Mass being constant,if volume increases density decreases and the water-vapour getting lighter goes up.There the temperature being less ,the water vapour condenses into water-droplets and floats as clouds,
919195
Evaporation is one of the two forms of vaporization. It is the process whereby atoms or molecules in a liquid state (or solid state if the substance sublimes) gain sufficient energy to enter the gaseous state. It is the opposite process of condensation.\n\nThe thermal motion of a molecule of liquid must be sufficient to overcome the surface tension and evaporate, that is, its kinetic energy must exceed the work function of cohesion at the surface. Evaporation therefore, proceeds more quickly at higher temperature, at higher flow rates between the gaseous and liquid phase and in liquids with lower surface tension (i.e. higher vapor pressure). Since only a small proportion of the molecules are located near the surface and are moving in the proper direction to escape at any given instant, the rate of evaporation is limited. Also, as the faster-moving molecules escape, the remaining molecules have lower average kinetic energy, and the temperature of the liquid thus decreases. This phenomenon is also called evaporative cooling. This is the reason that evaporating sweat cools the human body.\n\nGas has less order than liquid or solid matter, and thus the entropy of the system is increased, which always requires energy input. This means that the enthalpy change for evaporation (ΔHevaporation) is always positive. Evaporation is a cooling process.\n\nEvaporation is a critical component of the water cycle, which is responsible for clouds and rain. 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.\n\nEvaporation is one of the two forms of vaporization. It is the process whereby atoms or molecules in a liquid state (or solid state if the substance sublimes) gain sufficient energy to enter the gaseous state. It is the opposite process of condensation.\n\nThe thermal motion of a molecule of liquid must be sufficient to overcome the surface tension and evaporate, that is, its kinetic energy must exceed the work function of cohesion at the surface. Evaporation therefore, proceeds more quickly at higher temperature, at higher flow rates between the gaseous and liquid phase and in liquids with lower surface tension (i.e. higher vapor pressure). Since only a small proportion of the molecules are located near the surface and are moving in the proper direction to escape at any given instant, the rate of evaporation is limited. Also, as the faster-moving molecules escape, the remaining molecules have lower average kinetic energy, and the temperature of the liquid thus decreases. This phenomenon is also called evaporative cooling. This is the reason that evaporating sweat cools the human body.\n\nGas has less order than liquid or solid matter, and thus the entropy of the system is increased, which always requires energy input. This means that the enthalpy change for evaporation (ΔHevaporation) is always positive. Evaporation is a cooling process.\n\nEvaporation is a critical component of the water cycle, which is responsible for clouds and rain. 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.
164163
Evaporation is vaporization of a liquid below its boiling point.
821351
The water evaporates from the head (Maxwell-Boltzmann distribution)\nEvaporation lowers the temperature of the glass head (heat of vaporization) \nThe temperature drop causes some of the dichloromethane vapor in the head to condense \nThe lower temperature and condensation together cause the pressure to drop in the head (ideal gas law) \nThe pressure differential between the head and base causes the liquid to be pushed up from the base. \nAs liquid flows into the head, the bird becomes top heavy and tips over during its oscillations. \nWhen the bird tips over, the bottom end of the neck tube rises above the surface of the liquid. \nA bubble of vapor rises up the tube through this gap, displacing liquid as it goes \nLiquid flows back to the bottom bulb, and vapor pressure equalizes between the top and bottom bulbs \nThe weight of the liquid in the bottom bulb restores the bird to its vertical position
27398
You can observe this yourself by breathing on a mirror. As the condensation evaporates from the mirror, you have completed the water cycle. Water evaporates into the atmosphere from the ocean, lakes, rivers, and from soil and plants, and even from your skin and breath. When the air reaches saturation (100% humidity) due to cooling or changes in atmospheric pressure (or both) the water condenses  from vapor to liquid (or solid) and falls to earth as rain, snow, sleet, hail, or maybe only as dew. This water may then form streams and rivers and return to the ocean where it may evaporate again into the atmosphere or it may sink into the earth where it becomes groundwater that may take many thousands of years to emerge again, or may be pumped to the surface from a well and used for drinking water or irrigation. It is a continuous cycle that may take only seconds or may take thousands of years to complete the cycle depending on the path of the water.   \n\nWhy do I get the feeling I'm answering your homework question? Now if you'd asked about delta O18 (a heavy isotope of oxygen) I could have told you how the water cycle concentrates water composed of hydrogen and heavy oxygen atoms and how this is used to study paleoclimates using ice cores and sea shells. Have a good day.
240367
Endothermic.   It takes (heat) energy to vaporize a liquid.\n\nThink of evaporation from the skin.  It feels colder when you're wet.   It takes heat energy away (endothermic) from your skin when the water evaporates.
127632
Water vapor doesn't do much to stop a fire.  Liquid water will stop a fire because there is a big gap in the amount of energy in liquid versus gaseous water.  Hence, when liquid water evaporates, it sucks up a lot of energy, and makes that energy unavailable for combustion.  It can also, I believe, work to smother the flame by keeping oxygen off the fuel source (but don't quote me on that).\n\nHowever, you must reconize that you've named elements, not molecules.  If you have those three elements in the form of water and carbon dioxide, you have nothing to burn.  If your elements are in the form of molecular oxygen and oil, then it will.  If you've got molecular oxygen, molecular hydrogen, and coal, then you bet will burn!