latent heat問題一問

浪費能量, 好睇你點諗

不過用高溫火...湯會滾瀉lor

同埋有可能湯ge 溫度不一, 受熱不平均

其實你俾多少少資料我...可以最答出d...但我真係唔太知你想問乜

如需要再補充, 請寄信過來給我 :)

There are two factors explaining why it waste energy~

1. Specific Latent Heat of Vaporization
Surely you should understand that the specific latent heat of vaporization of water is high (2272 J/g). When the soup is boiling, energy is constantly lost to surrondings due to the temperature difference. As a result, constant heat energy should be supplied to the soup to keep it boiling. In this sense, energy is said to be wasted.

2. First Law of Thermodynamics
The first law of thermodynamics states that the increase in the internal energy of a thermodynamic system is equal to the amount of heat energy added to the system minus the work done by the system on the surroundings. Note that the water vapour due to boiling of soup has to do work against the atmosphere pressure in order to escape. Thus energy is consumed to do this work, which has no contribution to the boiling of soup. In this sense, energy is also wasted.

Hope the above information helps =)

Reference:
~ http://en.wikipedia.org/wiki/First_law_of_thermodynamics
~ http://en.wikipedia.org/wiki/Latent_heat