MidtermF09_Answers_PartB

MidtermF09_Answers_PartB - CHEM 1300 Midterm Part B, Fall...

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CHEM 1300 Midterm Part B, Fall 2009 (DO ALL QUESTIONS ON FRONT AND BACK) Name: ________________________ Student Number: ________________________ 1 As Se c. Ne Na c. Am Pu b. He At a. 75 33 0 1 75 34 0 1 19 10 19 11 0 1 241 95 241 94 4 2 217 85 221 87 + + + + + e e e Fr 1) If 8.52 g each of zinc, potassium dichromate, and sulfuric acid are reacted by the reaction: 4 Zn + K 2 Cr 2 O 7 + 7 H 2 SO 4 4 ZnSO 4 + 2 CrSO 4 +K 2 SO 4 + 7 H 2 O What is the limiting reactant and how many many mols of the limiting reactant are there? How many grams of potassium dichromate will be left unreacted? The molar masses of zinc, potassium dichromate, and sulfuric acid are respectively 65.41, 294.2 and 98.09 g/mol. Use the space below for your intermediate steps. Write your answers in the boxes given below Mols of K 2 Cr 2 O 7 = 8.52/294.2 = 0.0290 Mols of Zn = 8.52/65.41 = 0.130 mole ratio Zn/ K 2 Cr 2 O 7 = 0.130/0.0290 = 4.48 Mols of H 2 SO 4 = 8.52/98.09 = 0.0869 mole ratio H 2 SO 4 / K 2 Cr 2 O 7 = 0.0869/0.0290 = 3.00 From the above chemical equation it can be seen for a complete reaction one would need 7 mols of sulfuric acid and 4 mols of zinc for every mole of potassium dichromate. From the above calculated
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This note was uploaded on 12/19/2011 for the course AP CHEM 1300 taught by Professor James during the Fall '11 term at Manitoba.

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MidtermF09_Answers_PartB - CHEM 1300 Midterm Part B, Fall...

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