Work, Heat, and the First Law
****************************************
Work (w) is not a function of state.
***************************************************************
HEAT (q) That quantity flowing between the system and the
surroundings that can be used to change the temperature
of the system and/or the surroundings.
************************************************************************************************************
Sign convention: If heat enters the system, then it is positive.
Heat (q), like w, is a function of path. Not a state function
It is possible to have a change of state adiabatically (without heat transferred) or nonadiabatically.
*****************************************************************************************************************
Historically measured in calories
[1 cal = heat needed to raise 1 g H2O 1°C, from 14.5 °C to 15.5°C]
The modern unit of heat (and work) is the Joule. 1 cal = 4.184
************************************************************************************************************************
? The sum (w + q) is independent of path
? This implies that there is a state function whose differential is ?w + ?q
We define it as U, the “internal energy” or just “energy”
****************************************************************************************************************************
For fixed n, we just need to know 2 properties, e.g. (T, V), to fully
describe the system.
*****************************************************************************************************************************
المادة المعروضة اعلاه هي مدخل الى المحاضرة المرفوعة بواسطة استاذ(ة) المادة . وقد تبدو لك غير متكاملة . حيث يضع استاذ المادة في بعض الاحيان فقط الجزء الاول من المحاضرة من اجل الاطلاع على ما ستقوم بتحميله لاحقا . في نظام التعليم الالكتروني نوفر هذه الخدمة لكي نبقيك على اطلاع حول محتوى الملف الذي ستقوم بتحميله .
|