1023PracticeFinaExamlFall09MainCampusAnswerKey

1023PracticeFinaExamlFall09MainCampusAnswerKey - Dr. Jim...

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Dr. Jim Bloxton Chemistry 1023 Fall 2009 Practice Final Examination The actual number of questions on the Chem 1023 final exam will be less than the number in this sample practice final exam. This is a sample practice final examination which will cover WARD’S Kidney Dialysis Simulation Lab Activity; Solutions Preparation And Properties, Module 3 Acid-Base Chemistry: Part I: Determination of pKa Drug Product, Part II: Buffers, Parts III and IV Acidosis and Alkalosis experiments. These are only sample questions that may be on actual exams. This is not a comprehensive list of questions. Other questions or types of questions that are not contained in this practice final examination may be on exams. The final exam will cover all of the material that was covered in weeks 7, 10-12 in fall semester of 2009 and in the final exam review session of week 13. This includes all material that was covered in the laboratory, laboratory supplements, handouts, laboratory lectures, and laboratory experiments. It is strongly recommended that students work as many of the optional Bettleheim Chem 1021 lecture problems as is possible to help learn and review this material. Remember to learn the basic principles and then be prepared to apply the principles to new problems that you haven't seen before. All work must be shown to receive full credit. 1. What chemical conversions take place among the general components of a buffer system when small amounts of a strong acid are added to the buffer? H + + A - HA 2. HNO 2 is a weak acid. What is the formula for the conjugate base of HNO 2 ? NO 2 - 3. How can you make the meniscus more observable if you are having difficulty reading your buret? Place your hand, white paper towel or something that provides contrast behind the meniscus. 4. 1.0 mL of 1.0 M HCl is added to 100 mL of a sample of pure water? 1.0 mL of 1.0 M HCl is also added to 100 mL of a sample of a buffer solution. Which sample will have the greater change in pH? Explain. The sample of pure water will have a greater change in pH since the conjugate base in the buffer will neutralize some or all of the hydrogen ion from the HCl. The neutralization of the hydrogen ion in the buffer prevents as large of a change in pH as the pH change that occurs in a buffer. 5. What are the names and formulas of the components of the principle buffer system of the blood? H 2 CO 3 is carbonic acid and HCO 3 - is hydrogen carbonate ion or bicarbonate ion.
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2 6. What effect will the addition of a small amount of 0.10 M HI have on the pH of a buffer solution? Explain. HI is a strong acid which supplies hydrogen ion. Hydrogen ion will react with the conjugate base of the buffer system to produce more HA by the following equation: H + + A - HA This in turn makes the ratio [A - ]/[HA] smaller which makes the log[A - ]/[HA] less positive or perhaps negative and this when added to the pKa in the Henderson Hasselbach equation lowers the pH. 7. Is it possible to use the strong acid HCl and NaCl as components of a buffer system?
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1023PracticeFinaExamlFall09MainCampusAnswerKey - Dr. Jim...

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