calorimetry

Subject: calorimetry Fri Nov 28, 2008 7:55 pm

concise X says that :
farmers fill their fields with water to protect the crops from frost:water,having high specific heat capacity ,does not allow the temp. in the surrounding area of the plants to fall up to 0 degree centigrade .In the absence of water if on a cold night temp falls below 0,the water in the fine capillaries of plants will fall to 0 and it will freeze,so the veins will burst due to increase in vol. of water on freezing.
my question is that water in the capillaries of plants too have a high sp.heat capacity.then why is water needed from outside to lower the temp.?

Active member

actually the water that he fill the field with goes down in temprature and may go to o degree celcius. for each 1 degree fall in temprature 1 gram water will give out 336 joules of heat energy. so lot of water gives out lot of heat which keeps the atmosphere warm and does not allow water in cappilaries to freeze.

as you said, if you do not do anything, the water in the cappilary will freeze , even though it gives out heat to surrounding. that heat will not make the water itself to not freeze.it will only make the surrounding warm. just as the water in the foeld may freeze but the plants are protected.

hope you have understood. i am studying in mes udyogamandal school ,cochin, where i hope we have the best pysics & chemisstry teacher in the world. Abraham Thomas sir. he has a teaching experience of 46 years and explains everything in a perfect manner. so if you have any doubt in phy or chem feel free to ask me.

http://www.orkut.co.in/Main#Community.aspx?cmm=52615442