The tragic life of the First Law's discoverer.----Afterstudying the work habits, food intake and color of theblood of sailors in the tropics compared with those innorthern Europe, the young German doctor I. R. VonMayer concluded that amount of energy in food is usedboth to heat the body and to do work, and thus heat andwork represent energy in different forms. When hepublished these ideas, they were ridiculed, and Von Mayerbecame despondent Soon thereafter, James Joule, anEnglish brewer and amateur scientist, demonstrated theequivalence of heat and work experimentally but gaveVon Maver no credit for the idea...... Finally Von Maverreceived recognition for his great insight11
11 The tragic life of the First Law’s discoverer.-After studying the work habits, food intake and color of the blood of sailors in the tropics compared with those in northern Europe, the young German doctor I. R. Von Mayer concluded that amount of energy in food is used both to heat the body and to do work, and thus heat and work represent energy in different forms. When he published these ideas, they were ridiculed, and Von Mayer became despondent. Soon thereafter, James Joule , an English brewer and amateur scientist, demonstrated the equivalence of heat and work experimentally but gave Von Mayer no credit for the idea.Finally Von Mayer received recognition for his great insight
yaccumXwater bath焦耳定律实验装置12
12 vaccum 焦耳定律实验装置 water bath
打开旋钮，至达平衡。T水溶无变化，即Q=0即气体膨胀前后温度未变IE又:W=0.△U=Q-W=0即气体膨胀中内能不变，即U=f（T）C永很大,微小的放热难以测量，但实验证明气体原来的P越小，上式越正确。当P一→0时，上式完全正确即：理想气体的内能U仅为温度T的函数。13
13 打开旋钮，至达平衡。T水溶无变化，即Q = 0 即气体膨胀前后温度未变 又 ∵W = 0 ∴ △U = Q － W = 0 即气体膨胀中内能不变，即U = f (T) C水很大， ∴微小的放热难以测量，但实验证明气体原来的 P越小，上式越正确。当P → 0时，上式完全正确， 即:理想气体的内能U仅为温度T的函数
1-3 Heat of reaction1-3-1DefinitionConsidering a closed system which do volume work onlywhen the TreactantsTproducts' the absorbing heat / givingoff heatis called heat of reaction14
14 1-3 Heat of reaction 1-3-1 Definition Considering a closed system which do volume work only, when the Treactants = Tproducts，the absorbing heat / giving off heat is called heat of reaction
(1)Quantity ofheat at constant volume, Qv:AV=0, W=P△V=0△U=QvIts physical meaning is that in a constant volumereaction, the heat that the system absorbed is totallyused to increase its internal energy.15
15 （1） Quantity of heat at constant volume, Qv： △V = 0，W = P·△V = 0 △U=Qv Its physical meaning is that in a constant volume reaction, the heat that the system absorbed is totally used to increase its internal energy