S12_1252_Exam_2_Key

All calculated answers and work must include units

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Unformatted text preview: credit for problems involving calculations. All calculated answers and work must include units, and should be rounded to the appropriate number of significant figures! 88.91 1 A Free Response Instructions: Solve the following problems in the boxes provided below each question. Be sure to show all your work and units, and round your answers to the appropriate significant figures at the end of each part. 1. In a box of alkali metal chlorides (MCl), one container of salt has no label. To find the identity of the metal M, you dissolve 10.00 grams of MCl into 250.0 grams of water and find that the freezing point of the solution is 1.996 C. What is the identity of the metal, M? You must show work to get credit. 1.996 C = 0 C Tf Tf = 1.996 C FPsoln = FPsolvent Tf +1 correct Tf Tf = iKfm = (2)(1.86 C/m) 10.0 g MCl / MMMCl = 1.996 C 0.2500 kg H2O +1 H2O in kg +1 correct equation setup +1 i +1 Kf +1 MMMCl MMMCl = 74.55 g/mol +1 correct M MMM = 74.55 g/mol 35.45 g/mol = 39.10 g/mol M = potassium (K) 7 2. (a) A human who...
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