Final_Exam_2009_to_post

Final_Exam_2009_to_post - ChE 102 Final Exam Fall 2009 -...

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ChE 102 Final Exam – Fall 2009 - SOLUTIONS 7 1) A 1.00 g mixture of NaCl and CaCl 2 , which was completely dissolved in an aqueous solution, is treated with excess AgNO 3 to precipitate all of the Cl - ions present in solution as AgCl. A mass of 3.02 g of AgNO 3 was consumed in the precipitation process. What is the percentage by weight of NaCl in the original mixture? Data : M AgNO3 = 169.88 g/mol; M AgCl = 143.32 g/mol; M NaCl = 58.44 g/mol; M CaCl2 = 110.98 g/mol A) 12.5% B) 26.5% C) 37.5% D) 50.0% E) 75.0% 2) Water has a vapour pressure of 23.8 mmHg at 25ºC. An unknown amount of the non- volatile sugar glucose (C 6 H 12 O 6 ) is added to 1 kg of water and the vapour pressure of the system is found to decrease by 0.25 mmHg. What mass of sugar was added to the water? A) 191 g B) 106 g C) 57 g D) 38 g E) 19 g 3) The water-soluble non-electrolyte X has a molar mass of 410 g/mol. A 1.0-g mixture containing the non-electrolyte X and a sugar (with molar mass = 342 g/mol) is added to 10 g of water, to give a solution whose freezing point is -0.5 o C. Calculate the mass percent of X in the mixture. Data : K f ,water = 1.86 o C/m A) 20% B) 29% C) 34% D) 49% E) 19% 4) The reaction for the formation of gaseous hydrogen fluoride has an equilibrium constant of K C = 1.15 × 10 2 at a given temperature. Assuming that the reaction starts by adding 3.00 moles of each component (H 2 , F 2 , and HF) to a 1.5-L reactor, calculate the equilibrium concentration of hydrogen fluoride. H 2( g ) + F 2( g ) D 2 HF ( g ) A) 0.150 M B) 0.532 M C) 4.425 M D) 5.056 M E) 5.452 M 5) Studies on the equilibrium of the following reaction I 2( g ) D 2 I ( g ) were done in a 10 L reactor at 500
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Final_Exam_2009_to_post - ChE 102 Final Exam Fall 2009 -...

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