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Unformatted text preview: ECH 152A, Fall 2011, Roland Faller Midterm 1, October 21, 2011, 12:10 - 1:00 pm No books, No notes, only NONPROGRAMMABLE calculators, Maximum 30 points Attention: TWO Pages Problem 1 (5 points) A 50 g piece of gold (Au) is dropped from 10 m height into 200 g liquid mercury (Hg) at a place where the acceleration of gravity is g = 9 . 81ms- 2 . Everything starts at T = 25 C. What is the final temperature of the perfectly mixed gold mercury amalgamate. ( c p (Au) = 0 . 1291 J gK , c p (Hg) = 0 . 1395 J gK ) Solution Energy Conservation H final = H ( Au ) + H ( Hg ) + E pot ( Hg ) H = c p T So ( c p ( Au ) m ( Au )+ c p ( Hg ) m ( Hg )) T f = ( c p ( Au ) m ( Au )+ c p ( Hg ) m ( Hg )) T i + m ( Au ) gh leading to T f = ( c p ( Au ) m ( Au ) + c p ( Hg ) m ( Hg )) T i + m ( Au ) gh c p ( Au ) m ( Au ) + c p ( Hg ) m ( Hg ) = 298 . 14K = 25 . 14 C Problem 2 (9 = 3 2 + 3 points) (a) Which of these are state functions: Work, Volume, internal energy, Heat?...
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