A the melting range will be higher o c b the melting

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a. The melting range will be higher than 88-90 o C b. The melting range will be lower than 88-90 o C c. The melting range will be broader than 88-90 o C. d. Both A and C e. Both B and C 19. True or False: When measuring the melting point of an unknown compound, you only need to measure the melting point once. 20. What is the purpose of adding Na 2 CO 3 during the extraction of caffeine experiment? a. To react with caffeine to make sure it stays in the aqueous phase. b. To make sure caffeine stays deprotonated. c. To keep tannins in the organic phase. d. To raise the boiling point of the water. 21. What will be done to help with the sublimation of caffeine? a. The crude mixture will be heated b. The crude mixture will be placed under a vacuum c. Both a and b For the following 4 questions, consider the vapor composition diagram below for compounds A and B. 22. True or False: Compounds A and B form an azeotropic mixture. 23. What is the boiling point of B? a. 73 o C b. 65 o C c. 97 o C d. 100 o C 24. What is the boiling point of a solution with X B = 0.6? a. 80 o C b. 73 o C c. 93 o C 25. If a solution with a mole fraction of B of 0.9 is boiled what is the mole fraction of B in the vapors above the solution? a. 0.9 b. 0.05 c. 0.45 d. 0.75
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26. Predict the relative order of solubility for the following compounds in water (1 = most soluble, 4 = least soluble). a. 2,1,4,3 b. 1,2,3,4 c. 4,3,2,1 d. 1,3,4,2 27. In an infrared (IR) spectrum, higher wavenumbers are associated with _________________. a. Higher energy light b. Lower energy light c. There is no association between wavenumber and light energy 28. In an infrared spectrum, as bond strength increases, which of the following statements is true? a. The intensity of the absorption band will increase b. The intensity of the absorption band will decrease c. The frequency of the absorption band will increase d. The frequency of the absorption band will decrease 29.
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