Can't understand this... Ecology ?

Question

Water has a high specific heat and therefore it requires 1 calorie to heat up water 1cm3 by 1 degree celcius. Is 1 calorie really that much to take in?

Also when water evaporates, it needs a large amount of heat. Something like 584 calories per gram of water at 22 degrees celcius. How does that exactly cool the water? This is considered an evaporative cooler. What I am getting from this paragraph in my ecology textbook is that when water evaporates, it requires a lot of energy. As it takes this energy from its surroundings, the rest of the body of water is not taking as much energy and therefore is cooled. What if water never really evaporated, then water would be hotter?

Also, when water freezes it gives up a lot of energy to its environment.This is called the latent heat of fusion. 80 calories are given up as 1g of water freezes. The water enters a lattice state. A lattice state requires less energy since the molecules are not moving as quickly. How does this keep thermal stability of an aquatic environment. In fact it says this retards further cooling.

Answer 1

That's a lot of questions and comments; I'll take them one at a time:

"Water has a high specific heat and therefore it requires 1 calorie to heat up water 1cm3 by 1 degree celcius" - You have the concept backwards here. Forget what you think you know about calories because you got most of that from the fat-fighting industry, and they misuse the term. The definition of a calorie is the amount of heat required to heat 1cm3 of water by 1 degree Celcius. It is also frequently equated to an amount of a particular substance that, when burned, gives off 1 calorie of heat. It has nothing to do with eating or weight gain or weight loss. Coal is very high in calories, and so is gasoline. Neither one will make you fatter if consumed.

"Is 1 calorie really that much to take in?" - well, yes and no, depending on how you look at it. 1 calorie of butter is much more likely to contribute to depositing fat into fat cells than is 1 calorie of broccoli. The two are processed completely differently. 1 calorie of cellulose will not be processed at all, and will simply pass through the digestive system pretty much unchanged.

"Also when water evaporates, it needs a large amount of heat. Something like 584 calories per gram of water at 22 degrees celcius. How does that exactly cool the water?" - All substances require heat energy to induce evaporation at a given ambient temperature & pressure. Lava requires a great deal more energy than does water. Liquid nitrogen requires a great deal less. Water at usual life-supporting temperatures will not evaporate well unless the air contains very little water. So, if you have the combination of a body of water exposed to dry air, the water will evaporate into the air. For the water to go from its less excited liquid state to its more excited gaseous state, energy is required, and that energy is taken from its surroundings, in this case the surrounding water and/or air.

"What if water never really evaporated, then water would be hotter?" - yes, but evaporation is not the only factor; you have to consider that sunlight and volcanic vents to name a few also affect the temperature of the water. Without evaporation, the water would be relatively hotter than it would have been with evaporation.

"Also, when water freezes it gives up a lot of energy . . . How does this keep thermal stability of an aquatic environment. In fact it says this retards further cooling." - Just as evaporation removes energy from the surrounding water, freezing gives up energy to the surrounding water, literally causing the surrounding water to become warmer.The more the water freezes, the more heat energy is given up to the remaining unfrozen water.

Answer 2

Hmmm well i dont know that much about this proces, and i do try to understand what you have said. The problem is that we use the opesit metod to optain the energy? did i understod right? i mean you could get energy by cooling the water, not by boiling it?!... is strange for me becouse all i know is that you can get energy from water that evaporates becouse off the presure... i dont know how we could gather the energy by cooling it.

I hope i didnt said to much nonsense :)