Note: Real exam questions from 2012, Knowledge section, Morning session, Question 45
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45. For a system with K components and no chemical reactions, the number of independent heat balance equations that cannot be formulated is A K-1 B K C K+1 D 1. There can only be one heat balance equation; some people say that when the number of components is 2, K-1=1, so the options that cannot be used are BC – does this make sense?
This post was last edited by tjuliusuan on 2015-8-19 23:03. When K, K-1, or 1 equation is used, they can be independent of each other; the number of independent equilibrium equations is K
45: Correct answer: D. The number of independent equations is f=K-Q+2. Note that f>=0. When the system has one phase, Q=1 and f=K+1; when the system has 2 phases, Q=2 and f=K; when the system has 3 phases, Q=3 and f=K-1. When Q>=3, f
Hello upstairs, that’s the algorithm for degrees of freedom.
Thank you. Heh, only one value can be listed for energy; D is always correct. When K=1, B is correct ； When K=2, A is correct. But this is a multiple-choice question, so ABC should be selected; sometimes one shouldn’t get too fixated on things, haha