1021JDBMidtermExamII(Chapters 4, 6 and 8.6C,E 9th Edition)Fall2009B(AnswerKey)

1021JDBMidtermExamII(Chapters 4, 6 and 8.6C,E 9th Edition)Fall2009B(AnswerKey)

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Dr. Jim Bloxton Answer Key CHEM 1021 Fall 2009 Lecture Midterm II (Chapters 4 and 6 and 8.6C,E From 9 th Edition) Or (Chapters 5 and 7 and 9.6C,E From 8 th Edition) Please put your name, recitation day and time at the top of this exam. All work and calculations for all problems must be shown. Include proper units for each calculation. 1. Which solution has the higher osmolarity: 0.70 M (NH 4 ) 2 HPO 4 or 0.49 M KCl? Explain. Show all calculations. (NH 4 ) 2 HPO 4 (aq) 2NH 4 + (aq) + HPO 4 2- (aq) Three osmotically active particles in solution are formed from (NH 4 ) 2 HPO 4 (aq) . They are 2NH 4 + (aq) and HPO 4 2- (aq) . Total osmolarity of (NH 4 ) 2 HPO 4 (aq) is calculated as follows: 0.70 mol/L x 3 = 2.1 mol/L or 2.1 Osm (NH 4 ) 2 HPO 4 (aq . KCl (aq) K + (aq) + Cl - (aq) Two osmotically active particles in solution are formed from KCl (aq) . They are K + (aq) and Cl - (aq) . Total osmolarity of KCl (aq is calculated as follows: 0.49 mol/L x 2 = 0.98 mol/L or 0.98 Osm KCl (aq . The 0.70 M (NH 4 ) 2 HPO 4 solution with a 2.1 Osm has a higher osmolarity than 0.49 M KCl solution with a 0.98 Osm. 2. What is hemodialysis? Hemodialysis is a method to purify blood when kidneys fail. The blood is circulated out of the body and filtered through a machine and circulated back into the body. 3. Balance the following equation: Al + HBr AlBr 3 + H 2 2Al + 6HBr 2AlBr 3 + 3H 2
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4. Would you expect the polar molecule methanol, CH 3 OH, to mix with water? Explain. The alcohol, methanol, CH 3 OH, is a polar molecule that can form hydrogen bonds with the polar molecule water and will mix with water since there are less than 4 carbons for each OH group in methanol. 5. Is the strong base KOH a weak or strong electrolyte or a nonelectrolyte? Explain. The strong base KOH is a strong electrolyte since KOH almost fully ionizes or almost breaks apart 100% in solution to form K + and OH - ions as the major species. This process supplies lots of ions which will cause an aqueous solution to conduct electricity very well. The following information may be helpful for problems 6 - 7. Molar mass of Fe 2 O 3 = 159.7 g/mol. Molar mass of CO = 28.01 g/mol. Molar mass of
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This note was uploaded on 03/29/2011 for the course CHEMISTRY 1021 taught by Professor Jimbloxton during the Fall '09 term at Temple.

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1021JDBMidtermExamII(Chapters 4, 6 and 8.6C,E 9th Edition)Fall2009B(AnswerKey)

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