Midterm Exam Chem 6AL Your Name: ___________________ TA: ___________________ Do not open this exam until instructed to do so. On the Parscore sheet write and bubble in your name and Perm Number.Chem 6AL Midterm Exam Spring 2016 Name:____________________ TA: _____________________ Instructions: You may only have a pencil, a non-graphing/non-programmable calculator, and a Parscore sheet. Completely fill in each circle corresponding to your chosen answer. Use the Parscore to record your answers. On the Parscore sheet write and bubble in your perm #, and your name. There is a zero tolerance policy toward cheating. If you are caught cheating in any way (including, but not limited to, having notes or cell phone out or looking at someone else’s exam) your exam will be taken away and you will receive a zero. There are 35 questions. For true/false questions, A = True, B = False. 1. What is the best definition of a corrosive compound? a. Readily explodes b. Readily catches fire when exposed to air c. Can cause damage to developing fetuses d. Readily destroys body tissue and/or metal e. Readily induces vomiting 2. True or False: In the four-diamond system of chemical hazards higher numbers represent more dangerous hazards. 3. In what waste container would you place a used solution of acetone and water? a. Organic b. Aqueous c. Down the drain 4. In lab a student asks you to hand her a bottle of ether. Which compound should you give her? a. CH3OCH2CH3 b. CH3CH2OCH2CH3 c. CH3OCH3 d. CHCL3 e. CH2Cl2 5. The toxicity encountered from a lifetime of smoking is an example of the _________ toxicity associated with smoking. a. Chronic b. Acute c. Teratogenic 6. Below are some of the hazards associated with HCl. Which hazard is the main reason that HCl must be used in the fume hood? a. HCl can cause severe damage to lung b. HCl causes metals to corrode c. HCl can cause severe skin damage7. Which solvent is the most miscible with water? a. Hexane b. Ether c. Methylene chloride d. Acetone e. C and D are both very miscible with water 8. Which amine would have the highest boiling point? B 9. When measuring a melting point, you can generally raise the temperature quickly until you get close to the expected melting point range. Generally, how close to the melting point range should you start to slow down the rate of heating? a. Within 5 oC b. Within 10 oC c. Within 20 oC d. Within 30 oC e. Within 50 oC 10. When two liquids are mixed and form two separate layers, the liquids are said to be ____________. a. Miscible b. Immiscible 11. Rank the following compounds from most soluble to least soluble in water. a. 4>1>3>2 b. 1>2>3>4 c. 4>2>3>1 d. 1>4>3>2 e. 4>1>2>3 12. 4-Ethylbenzoic acid will be soluble in which of the following solvents? (select all that apply) a. Ether b. 3M NaOH c. 3M NaCl d. 3M HCl e. All of the above 13. True or False: Heating a mixture to boiling very slowly can help avoid azeotropes when performing a distillation. 14. Which one of the following statements is true concerning distillation? a. Simple distillation requires more energy than fractional distillation. b. Column holdup is the reason simple distillation give less pure compounds. c. As you increase the length of a fractional distillation column, you increase the ability to avoid azeotropes. d. When measuring the temperature of the vapors during a simple distillation you will notice a gradual increase in the temperature. e. All of the above statements are true.15. Consider the temperature composition diagram below for compounds A and B. If a mixture of compounds A and B with a mole ratio of B equal to 0.70 prepared, what is the boiling point of this mixture? a. 83 oC b. 75 oC c. 95 oC d. 73 oC 16. If the vapors above the mixture are collected and condensed, what would be the mole ration of B in this newly formed liquid? a. 0.9 b. 0.6 c. 0.7 d. 0.2 e. 0.1 17. True or False: A and B form an azeotrope. 18. Consider a mixture of 0.120 moles ethyl acetate (MW = 88.1 g/mol, density = 0.897 g/mL, Po = 11.9 kPa) and 20.0 mL of hexane (MW = 86.2 g/mol, density = 0.66 g/mol, Po = 19.1 kPa). What is the partial pressure of hexane in the vapor above the solution? a. 10.7 kPa b. 24.4 kPa c. 14.2 kPa d. 5.2 kPa 19. What is the mole fraction of hexane in the vapor above the solution in the previous question? a. 0.72 b. 0.67 c. 0.82 d. 0.32 20. You have a mixture of the two compounds shown below dissolved in ether. If you want to extract the compound on the right out of the organic phase, which of the following should you add? a. 3M NaCl b. Distilled Water c. 3M NaOH d. 3M HCl e. Dichloromethane 21. Which of the options below would not help resolve an emulsion? a. Wait patiently b. Shake the solution vigorously c. Add brine d. Gently stir the solution 22. For a recrystallization solvent to work, your impurities should be _______ at cold temperature and ________ at hot temperatures. a. Soluble, insoluble b. Insoluble, insoluble c. Soluble, soluble d. Insoluble, soluble 23. True or False: If you use too much solvent during a recrystallization, the main problem you will encounter is that your product will be less pure than if you had used the correct amount of solvent.24. Rapid cooling of the mother liquor during a recrystallization will result in _______ crystals than if you had used slow cooling. a. Smaller b. More pure c. Less pure d. Both a and b e. Both a and c 25. Consider a 4.5 gram sample of caffeine dissolved in 60mL of water. The partition coefficient for caffeine between dichloromethane and water is approximately 8.1. If caffeine is extracted by using 3, 10mL portions of dichloromethane, what is the maximum possible about of caffeine that can be extracted? a. 4.15 g b. 4.49 g c. 4.42 g d. 4.28 g 26. In Experiment 4a (Caffeine Isolation) you added (or will add) Ca(OH)2. Suppose the stockroom was out of this compound. Which one of the choices below would be a suitable substitute? a. CaCl2 b. Brine c. 3M HCl d. NaOH 27. Sublimations happen more readily at _____ pressures than at ________ pressures. a. High, low b. Low, high 28. Which compound would have the highest wavenumber (cm-1) C=O stretch? D 29. Which of the following does not affect the intensity of an IR absorption band? a. Concentration b. Dipole moment c. Bond order d. Number of bonds 30. True or False: Lighter atoms give rise to