Final Exam Chem% - Final Exam Chem 212 Fall 2005 Name(Please Print Clearly Show your work on numerical problems if you wish to receive any credit

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Final Exam Chem 212 Fall 2005 Name______________________________________ (Please Print Clearly) Show your work on numerical problems if you wish to receive any credit. 1) You want to prepare 500mL of a solution containing 2.50 ppm Fe +2 . How many grams of ferrous ammonium sulfate hexahydrate (NH 4 ) 2 Fe (SO 4 ) 2 • 6 H 2 O; F.W. = 392.14 g/mol ± 0.03 g/mol) must be dissolved and diluted to 0.500L in order to get a 2.50 ppm solution of Fe +2 . What is the molarity of the Fe +2 in the 2.50 ppm solution? g (NH 4 ) 2 Fe (SO 4 ) 2 • 6 H 2 O required = ____________________________________ [Fe +2 ] = ___________________________________ If the uncertainty associated with the 500 mL volumetric flask is ± 0.02 mL and the uncertainty associated with weighing out the (NH 4 ) 2 Fe (SO 4 ) 2 • 6 H 2 O is ± 0.001 g, what is the uncertainty associated with the molarity of the ferrous ammonium sulfate solution.
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120 125 130 135 140 145 150 155 160 165 170 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 2) a) Two methods were used to measure the [Ca +2 ] of drinking water . Based on the data given below, are the two methods give significantly different results at the 95% confidence level? Method 1 results: 139, 147, 160,158,135 (mean = 147.8; s. dev. = 11.12) Method 2 results: 148, 159,156,164,159 (mean = 157.2; s. dev. = 5.89) b) State the null hypothesis for the comparison in part a). Sketch the gaussian distribution of the [Ca +2 ] measurements for the two methods on the axes shown below (make sure to label the distributions as to which method is represented by which curve). Which method is more accurate (briefly justify your answer)?
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3) A 25.0 mg sample of a compound with a molecular weight of 251.53 was dissolved in water and diluted to the mark using a 50 mL volumetric flask. A 7.00 ml aliquot was withdrawn, placed in a 100 mL volumetric flask, and diluted to the mark. a) What is the concentration of the solution in the 50 mL flask?
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This note was uploaded on 02/16/2010 for the course CHEM 589 taught by Professor -1 during the Fall '02 term at Pennsylvania State University, University Park.

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Final Exam Chem% - Final Exam Chem 212 Fall 2005 Name(Please Print Clearly Show your work on numerical problems if you wish to receive any credit

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