tailieunhanh - An Introduction to Thermodynamics phần 10

trong đó áp lực xuất hiện như là một xấp xỉ cho các hoạt động, thường là bằng văn bản của KP (và, bởi vì áp lực thay thế cho các hoạt động dimensionless, KP có thể có kích thước rõ ràng quyền hạn của áp lực). Hãy xem xét tại các vấn đề của việc tìm kiếm các áp lực cân bằng oxy trên Ag | but this would be a violation of the third law which says that A and B must have the same entropy at absolute zero. The only other possibility is that T1 0. That is the transition A T1 - B 0 can occur only if T1 is zero one cannot reach absolute zero from a non-zero temperature. The same argument may be turned around. If SB were greater than SA0 then T1 would be greater than zero and it would be possible to reach absolute zero. If T1 must be zero then it follows that SA o Sb0. Therefore the following statement may be considered as an alternative form for the third law of thermodynamics It is impossible by any procedure no matter how idealized to reduce any system to the absolute zero in a finite number of operations. 7 10 07 5- 118 Appendix Basic Operations of Calculus Calculus is an old term for calculations. It is now applied to the methods of mathematics developed by Isaac Newton and by Gottfried Wilhelm Leibniz. Many problems of physics chemistry and engineering require an understanding not only of the operations of calculus but also of the justification and the limitations for these operations. Such questions are properly treated in mathematics texts. This appendix is in no way a substitute for such a rigorous development of calculus. It is rather a temporary expedient to allow the student who has not yet reached some of these operations in his mathematics studies or has forgotten some details to apply those particularly simple operations that are required in elementary thermodynamics. What makes calculus different from ordinary algebra is that it looks at the limiting values of quantities including infinite1 numbers of quantities or steps. Provided the mathematical expressions are well behaved the resulting equations are no more difficult than algebra. Functional Notation Whenever the value of one quantity or variable depends on the value of some other quantity or variable the first variable is said to be a function of the second. This is often written y