2007-02-25 15:45:16 · 5 answers · asked by bluerosesea 1 in Environment
The evaporation of water requires heat to break the hydrogen bonds that join the water molecules together. This thermal energy is taken from the water molecules, and then transferred to the air, thus causing a lowering of the temperature of the water surface.
This is how sweat cools a person's body.
PS. Dan - I see what you're saying, but I think you misunderstand. By breaking of the hydrogen bonds, I don't mean that the Oxygen and Hydrogen atoms are split from each individual molecule. The hydrogen bonds are what join individual water molecules together. Hydrogen bonds are a weaker type of bonding that is between individual water molecules. Each individual water molecule can bond with 4 others. The hydrogen bonds is what makes water "sticky." When they are broken through evaporation, the water that has just evaporated is still H20. When they are broken, the water evaporates, but it is still water. When water evaporates, it has high amount of thermal energy. The evaporation occurs because there is too much energy to maintain the hydrogen bods between molecules. On the other hand, when water is ice, there is little thermal energy, so the hydrogen bonds are the strongest and the maximum amount of bods form.
Hydrogen bonding is an interesting topic. It is responsible for many things. It even holds the double helix structure of dna strands together.
Cheers :)
2007-02-25 15:53:08 · answer #1 · answered by Anonymous · 0⤊ 0⤋
The water will only evaporate if the air is warmer than the water. Therefore, when the cooler water turns to a gas, mixing with the surrounding warmer air, it removes some of the heat in the air. Same prinicipal as how an air condition works, it's a simple exchange of heat.
2007-02-25 15:56:21 · answer #2 · answered by hgw_1972 2 · 0⤊ 0⤋
here's a simple answer. The heat that caused the evaporation was transfered to the water. Hence the lower temp.
2007-02-25 15:51:34 · answer #3 · answered by Hecaeta 3 · 0⤊ 0⤋
PS, spooled - Evaporation of water does not break the hydrogen bonds; that requires far greater energy. If it did, steam from boiling water would be highly explosive since it would be composed of hydrogren and oxygen molecules, both flammable in their pure states.
2007-02-25 16:05:03 · answer #4 · answered by Dan 3 · 0⤊ 0⤋
Its the same reason ice that melts makes the water stay cold.
The air stays cool because its lighter than the liquid that is being heated.
2007-02-25 15:54:34 · answer #5 · answered by Sore wa himitsu desu! 3 · 0⤊ 0⤋