1. Which molecule will have the strongest intermolecular forces? _D. 2. Which molecule will have the weakest intermolecular forces?

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Use the following information to answer questions 1-5: 1. Which molecule will have the strongest intermolecular forces? _D 2. Which molecule will have the weakest intermolecular forces? _C 3.

1 Use the following information to answer questions 1-5: 1. Which molecule will have the strongest intermolecular forces? _D 2. Which molecule will have the weakest intermolecular forces? _C 3. What is the strongest intermolecular force present in molecule A? A. dispersion B. dipole-dipole C. hydrogen bonding D. ion-dipole 4. Which molecule will have the lowest boiling point? _C 5. Which molecule will have the lowest vapor pressure? _D

What phenomenon is occurring to 1-propanol from point B to point A? A. melting B. liquid warming C. freezing D. solid cooling 8.

2 Below is the heating curve for 1-propanol (C3H8O 60.1 g/mol). Use this information for questions 6-9: 6. What is the approximate boiling point of 1-propanol? A C B. 250 C C. 95 C D. 20 C 7. What phenomenon is occurring to 1-propanol from point B to point A? A. melting B. liquid warming C. freezing D. solid cooling 8. Where would condensation be found on the heating curve? A. B à C B. E à D C. C à D D. E à F 9. If 45.6 kj is released when kg of 1-propanol freezes (at the freezing point), what is the enthalpy of fusion (kj/mol)? A B C D. 6.44

10. Which plot best describes the relationship between ln(pvap) vs 1/T? 11. The Hvap of hexane (C6H14 86.18 g/mol) is 28.85 kj/mol.

3 10. Which plot best describes the relationship between ln(pvap) vs 1/T? 11. The Hvap of hexane (C6H g/mol) is kj/mol. If the normal boiling point is 68 C, what is the boiling point at 325 Torr? A C B C C C D C A 12. True or False: The viscosity of a liquid increases with increasing temperature. A. True B. False 13. Which vapor pressure (at 25.0 C) would be associated with the highest boiling point? A atm B atm C atm D atm 14. What is the strongest intermolecular force present in an aqueous KCl solution? A. dispersion B. dipole-dipole C. hydrogen bonding D. ion-dipole

4 15. At room temperature Cl2 is a gas, Br2 is a liquid, and I2 is solid. All three molecules are diatomic halogens. What IMF is present in each molecule? How could IMF help explain why they are each a different state of matter? Each molecule has dispersion forces. The strength of the dispersion force increases as you go down the halogen column. Cl2 has the weakest dispersion force (smallest ion) while I2 has the strongest dispersion force (largest ion). Thus more energy (higher temperature) is required to overcome dispersion forces to allow more separation and movement between the molecules. 16. How much energy is required to raise the temperature of g of water from 40 C to 120 C? g à 2 mol H2O q = (36.02 g)(4.184 J/mol C)( C) = 9042 J kj = 2 mol * kj/mol = 81.3 kj = J q = (36.02 g)(1.997 J/mol C)( C) = 1797 J Total E = 9.21 x 10 4 J or 92.1 kj 17. Which of the following statements is true regarding solubility? A. We can expect substances with positive DHsoln always to be soluble. B. We can expect substances with positive DHsoln to be soluble only if the entropy of solution is negative. C. We can expect substances with negative DHsoln always to be soluble. D. None of the above are true. 18. Which of the following statements would you expect to be most soluble in hexane, C6H14? A. NH3 B. CaCl2 C. CH3Cl D. CH3(CH2)3CH3 19. The DHsoln of CsCl(s) is kj/mol. The DHlattice for CsCl(s) is kj/mol. The DHhydration of CsCl is A kj/mol B kj/mol C kj/mol D kJ/mol 20. Compared to the DHsoln of CsCl, the DHsoln of KCl would be A. more endothermic B more exothermic C. the opposite sign D. you can t tell

5 21. (6 points) The partial pressure of O2 in your lungs is around 25 Torr. The Henry s law constant for O2 in water at 25 C is 1.66 x10-6 M/Torr. What concentration of O2 can dissolve in 1.0 L of water at 25 C if the partial pressure of O2 is 25 Torr? Sgas = kh Pgas =(1.66 x 10-6 M/Torr)(25 Torr) = 4.15 x 10-5 M 22. If you wanted to increase the concentration of O2 dissolved in water, you could A. increase the temperature. B. lower the temperature. C. increase the amount of water. D. you can t change the concentration; Henry s law constant is a constant 23. (6 points) A solution is made by dissolving 27.2 g urea (CH4N2O, g/mol), a nonelectrolyte, in 260. g water. At what temperature will this solution boil? (The molal boiling point constant, kb, for water is 0.51 C kg/mol.) 27.2 g urea (1 mol/60.6 g) = moles of urea Molality = moles/0.260 kg solvent = mol/kg DTb = m x kb = mol/kg x 0.51 C kg/mol = 0.88 C Water normally boils at C, and the soluite will elevate that, so = C 24. You prepare 1.0 M solutions in water of the following solutes. With which solute is the solution likely to freeze at the lowest temperature? A. Ethylene glycol, HOCH2CH2OH B. Sodium chloride, NaCl C. Chloromethane, CH3Cl D. Calcium chloride, CaCl2 25. An animal cell assumes its normal volume when it is placed in a solution with a total solute molarity of 0.3 M. If the cell is placed in a solution with a total solute molarity of 0.5 M, A. no movement of water takes place. B. water flows from low solute concentration to high solute concentration. C. water flows from high solute concentration to low solute concentration. D. what happens depends on the specific identity of the solute molecules. 26. Into about how many moles of ions does 1 mole of AlCl3 dissociate in water? A. 1 B. 2 C. 3 D. you can t predict Really the answer should be 4. Of the answers given, C or D would be best.

6 27. (4 points) A solution of glucose (C6H12O6) was prepared by dissolving 25.0 g of glucose in g of water at a temperature of 25 o C. The mass percent of glucose in the solution is: A B C D (4 points) Biphenyl (C12H10) is a non-volatile, non-ionizing solute that is soluble in benzene (C6H6). At 25 C, the vapor pressure of pure benzene is Torr. What is the vapor pressure of a solution made from dissolving 15.6 g of biphenyl in 30.8 g of benzene? A Torr B Torr C Torr D Torr

7 Useful information: 1 atm = 760 mmhg 1 mmhg = 1 torr 0 ºC = 273 K R = J/(mol K) = (L atm)/(mol K) æ P ö ln ç 2 = è P1 ø - DHvap é ê R ë 1 T2 1 ù - ú T1 û lnpvap = - D H vap R æ 1 ç è T ø ö + ln b DHsolution = DHlattice + DHhydration Psolution = XsolventP o solvent Xsolvent + ixsolute = 1 H 2O : C s (gas) = 1.84 J/g ºC C s (liquid) = 4.18 J/g ºC C s (solid) = 2.09 J/g ºC H vap = kj/mol H fus = 6.01 kj/mol

PX-III Chem 1411 Chaps 11 & 12 Ebbing

PX-III Chem 1411 Chaps 11 & 12 Ebbing 1. What is the name for the following phase change? I 2 (s) I 2 (g) A) melting B) condensation C) sublimation D) freezing E) vaporization 2. Which of the following