DATA THAT YOU MAY USE UNITS Conventional Volume ml or cm 3 = cm 3 or 10-3 dm 3 Liter (L) = dm 3 Pressure atm = 760 torr = Pa CONSTANTS

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1 DATA THAT YOU MAY USE UNITS Conventional S.I. Volume ml or cm 3 = cm 3 or 0-3 dm 3 Liter (L) = dm 3 Pressure atm = 760 torr = Pa torr = 33.3 Pa Temperature C 0 C = 73.5 K PV L-atm = dm 3 Pa =0.3 dm 3 kpa =0.3 J Energy cal = 4.84 J (J= kg m /s ) erg = g cm /s = 0-7 J Current ampere (A) = C/s CONSTANTS Avogadro s number N 6.0 x 0 3 mol - Boltzmann s constant k.38 x 0-3 J K - Faraday s constant F C mol - Values of R for various unit combinations.987 cal mol - K L atm mol - K cm 3 atm mol - K J mol - K erg mol - K dm 3 kpa mol - K cm 3 kpa mol - K - Useful gas equations: P ln P ΔH = R T T vap PV = nrt m = MPV RT P = 3 N V mu PV n T P V = n T d = MP RT 3RT u rms = P = hdg M e k = 3 RT N A

2 Integrated Rate Laws: Arrhenius Equation: Order 0: [A] = [A] 0 - kt Order : [A] = [A] 0 e - k T ln a / k = Ae E RT k E a = k R T T Order : /[A] = /[A] 0 + kt ΔG (non-standard conditions): ΔG = ΔG + RT ln Q Van t Hoff Equation: o K ΔH ln = K R T T The Periodic Table of the Elements

3 ) Surface tension is thought to be due to: A) surface molecules having lower energy than bulk molecules B) surface area trying to increase C) air absorbed on the surface D) solute concentrated on the surface ) The property of a liquid that measures its resistance to flow is called: A) viscosity B) polarizability C) wetability D) resistivity E) capillarity 3) The process in which a gas is transformed into a solid is called: A) solidification B) deposition C) condensation D) vaporization 4) The heat of fusion for napthalene (C 0 H 8 ) is 8.98 kj mol - and for sodium is.60 kj mol -. The amount of heat that would melt 37.0 grams of napthalene would melt how many grams of sodium? A) 48.4 g B) g C) 8.3 g D) 70. g E) 50 g 5) Given the data below, determine the normal boiling point of COCl : P = 00 mm Hg, T = C, ΔH vap = 7.4 kj mol - A) 5.0 C B) -65. C C) -5.0 C D) 78 C E) C 6) A liquid has a molar heat of vaporization of.7 kj mol -. Its normal boiling point is 459K. What is the vapor pressure, in mmhg, at 70 C? A) 7.48 B) 580 C) 56.8 D) 74 E) 0

4 7) When the vapor pressure of a liquid equals atmospheric pressure, the temperature of the liquid equals: A) the boiling point B) the normal boiling point C) 00 C D) the vaporization point 8) Flask A has a volume of 0.50 L and contains 50 g of a volatile liquid. Flask B has a volume of.0 L and contains 5 g of the same liquid. Both flasks are stoppered and both are at 30 C. The ratio of the vapor pressure of the liquid in Flask A to that in Flask B is: A) : B) :4 C) : D) 4: E) : 9) At the triple point of substance W, the enthalpy of fusion 9.5 kj mol - and the enthalpy of sublimation is 8.9 kj mol -. What is the heat of vaporization under these conditions? A) 8.9 kj mol - B) -8.9 kj mol - C) -9.5 kj mol - D) 38.4 kj mol - E) 9.4 kj mol - 0) If the triple point of substance W occurs at a pressure of 065 torr, which of the following statements is definitely true: A) W is gaseous at room temperature B) W cannot be liquified under atmospheric pressure at any temperature C) W is a non-permanent gas D) W cannot be liquefied at room temperature under any pressure ) Which compound is most likely to be soluble in water? A) ethylene glycol (HOCH CH OH) B) benzene (C 6 H ) C) hexane (C 6 H 4 ) D) butyl alcohol (CH 3 CH CH CH OH) E) iodine (I )

5 ) A solution is called ideal when: A) the forces of attraction between solute and solvent molecules are somewhat smaller than between solute-solute molecules or solvent-solvent molecules. B) the forces of attraction between solvent molecules exceed those between solute and solvent molecules. C) the forces of attraction between solute molecules exceed those between solute and solvent molecules. D) the forces of attraction between solute molecules and solvent molecules are much smaller than between solute-solute molecules or solvent-solvent molecules. E) all intermolecular forces of attraction are the same, resulting in no net enthalpy change when the solution is formed from its components. 3) Henry s Law constants for aqueous solutions at 5 C are molal/mmhg for N and molal/mmhg for O. Determine the solubility of oxygen in water under an atmospheric pressure of 760 mmhg, assuming that air is 80% N and 0% O, by mole. A) m B) m C) m D) m E) m 4) An azeotropic mixture is a: A) liquid mixture of two or more substances linked by azide functional groups. B) solution of two or more substances present in the same amounts in the liquid phase. C) solution of two or more substances that cannot be made to freeze. D) mixture of two or more substances where boiling point cannot be determined. E) liquid mixture of two or more substances in which the vapor has the same composition as the liquid. 5) Which of the following is NOT a colligative property? A) boiling point elevation B) osmotic pressure C) freezing point depression D) solubility 6) Moles of solute per mole of solution is a definition of: A) percent by weight B) molality C) mole fraction D) molarity

6 7) Commercial nitric acid is 6.0 M HNO 3 (aq) and has a density of.4 g/ml. What is the mole fraction of HNO 3 in this solution? A) B) C) 0.4 D) E) ) The vapor pressures of pure hexane and pure heptane at 5 C are 5.4 mmhg and 45.6 mmhg respectively. A solution contains mol fraction hexane and 0.00 mol fraction heptane. What is the composition of the vapor in equilibrium with this solution at 5 C? A) 77.0% hexane, 3.0% heptane B) 45.0% hexane, 55.0% heptane C) 50.0% hexane, 50.0% heptane D) 80.0% hexane, 0.0% heptane E) 93.0% hexane, 7.0 % heptane 9) g of a compound with the empirical formula C H N is dissolved in 0.00 g benzene. The resulting solution freezes at 4.99 C. Benzene freezes at 5.48 C and has a freezing point depression constant of K f = 4.90 C/m. What is the molecular formula of the compound? A) C 3 H N B) C 6 H 6 N 3 C) C 3 H 3 N D) C 4 H 4 N E) C 8 H 8 N 4 0) Adding a non-volatile solute such as NaCl to ice will cause it to melt by: A) increasing both the rate of fusion and, to a lesser extent, the rate of solidification. B) decreasing the rate of fusion. C) increasing the rate of fusion. D) decreasing the rate of solidification. E) increasing the rate of solidification. ) We wish to lower the freezing point of the water in an automobile radiator to -40 C. The total mass of water present is.0 kg. For which one of the following compounds would we have to use the greatest mass of solute to achieve this? You may assume that K f for water = -.86 C/m and that all ionizable solutes are completely ionized with unit activity even at this high concentration. A) AlF 3 (M.W. = 84 g/mol), i = 4 B) C H 5 OH (M.W. = 46 g/mol), i = C) NaCl (M.W. = 58.5 g/mol), i = D) C 3 H 6 (OH) (M.W. = 76 g/mol), i = E) CaCl (M.W. = g/mol), i = 3

7 ) The solubilities of potassium perchlorate, KClO 4, in water at 0 C, 0 C, and 80 C are as follows: T ( C) Sol. g KClO 4 /00 g H O Which of the following fractional crystallization schemes would produce the highest percent yield for the recrystallization of potassium perchlorate? A) A solution containing 7 g KClO 4 in 00.0 g H O at 80 C is cooled to 0 C. B) A solution containing.4 g KClO 4 in 00.0 g H O at 0 C is cooled to 0 C. C) A solution containing.4 g KClO 4 in 00 g H O at 80 C is cooled to 0 C. D) A solution containing 7 g KClO 4 in 75 g H O at 80 C is cooled to 0 C. E) A solution containing g KClO 4 in 00 g H O at 80 C is cooled to 0 C.

8 ) E ) A 3) B 4) A 5) A 6) E 7) B 8) C 9) E 0) B ) A ) E 3) A 4) E 5) D 6) C 7) C 8) E 9) D 0) D ) D ) E

MCGILL UNIVERSITY FACULTY OF SCIENCE MIDTERM EXAMINATION CHEM 120 MONDAY MARCH 16, :30PM 8:30PM VERSION NUMBER: 1

MCGILL UNIVERSITY FACULTY OF SCIENCE MIDTERM EXAMINATION CHEM 120 MONDAY MARCH 16, 2009 6:30PM 8:30PM VERSION NUMBER: 1 Instructions: BEFORE YOU BEGIN: Enter your student number and name on the computer