1. How many of the following compounds will exhibit hydrogen bonding?

Transcription

1 Spring 2002 Test 1 1. ow many of the following compounds will exhibit hydrogen bonding? N A. 1 B. 2 C. 3 D. 4 E. 5 N C 3 Cl N N C O OC 2 C 2 O 2. Which of the following is indicative of the existence of strong intermolecular forces of attraction in a liquid? A. a very low boiling point B. a very low vapor pressure C. a very low viscosity D. a very low heat of vaporization E. a very low freezing point 3. Which of the following would be expected to have the lowest heat of vaporization? A. 2 O B. N 3 C. P 3 D. As 3 E. C 4 4. Which of the following statements is/are correct? I. Mercury has a meniscus that curves upwards (convex) II. Water has a meniscus that curves upwards (convex) III. The density of all solids is great than the density of their liquids A. I only B. II only C. III only D. I and III only E. II and III only 5. Which one of each of the following pairs would be more soluble in water? I. C 3 O or C 4 II. NaCl or AgCl; III. C 3 C 2 O or C 3 C 2 C 2 C 2 C 2 C 2 C 2 C 2 C 2 O

2 A. C 3 O, NaCl, C 3 C 2 C 2 C 2 C 2 C 2 C 2 C 2 C 2 O B. C 3 O, NaCl, C 3 C 2 O C. C 4, NaCl, C 3 C 2 O D. C 4, AgCl, C 3 C 2 C 2 C 2 C 2 C 2 C 2 C 2 C 2 O E. C 3 O, AgCl, C 3 C 2 O 6. Which of the following statements is/are true? I. Because ionic forces are so much stronger than hydrogen bonds, no ionic compound will be soluble in ethanol (C 3 C 2 O) II. Making of any solution in which a solid is dissolved in a liquid will always have a positive entropy. III. the heats of hydration of ions increase (become more exothermic) as ionic charge increases A. I and II only B. I and III only C. II and III only D. all three are true E. none are true 7. Which of the following statements is/are true? I. Supersaturated solutions are very stable II. The solubility of gases in liquids increases as the temperature is raised III. The solubility of gases in liquids is independent of the external pressure A. I and II only B. I and III only C. II and III only D. all three are true E. none are true 8. A solution is made by dissolving 27.8 g of nicotine (Molar Mass = 160 g/mol) in 145 g of cyclohexane (C 6 12 ) to form 142 ml of solution. Calculate the mole fraction of the solute and the molarity, respectively, of this solution. A , 1.22 M B , 12.1 M C , 1.22 M D , 1.22 M E , 12.1 M 9. An aqueous solution of hydrogen peroxide ( 2 O 2 ) that is 30.0% by mass has a density of 1.11 g/ml. Calculate the molality of this solution. A m B m

3 C m D m E m 10. A solution is made by dissolving 12.0 g of glucose (Molar mas = 180. g/mol) in 52.0 g of ethanol. Given that the normal boiling point of ethanol is 78.5 o C, and the value of K b of ethanol is 1.22 o C /m, calculate the boiling point of the solution. A o C B o C C o C D o C E o C g of an unknown biological molecule is dissolved in enough water to make 22.0 ml of solution. At 25.0 o C, the osmotic pressure is measured to be 28.0 torr. Calculate the molar mass of the unknown. A g/mol B g/mol C g/mol D. 11,240 g/mol E. 33,800 g/mol 12. Which of these solutions 0.1 m NaCl, 0.15 m glucose, 0.1 m Ca(NO 3 ) 2 would have I. the highest vapor pressure II. the lowest boiling point A. 0.1 m CaCl 2, 0.1 m CaCl 2 B m glucose, 0.1 m CaCl 2 C. 0.1 m CaCl 2, 0.15 m glucose D m glucose, 0.15 m glucose E. 0.1 m NaCl, 0.1 m CaCl For the first order reaction 2N 2 O 5 (g) => 4NO 2 (g) + O 2 (g), at the time the rate of consumption of N 2 O 5 is measured as 1.2 x 10-4 M/s, what is the rate at which NO 2 is being formed? A. 1.2 x 10-4 M/s B. 2.4 x 10-4 M/s C. 6.0 x 10-5 M/s D. 3.0 x 10-5 M/s E. 4.8 x 10-4 M/s

4 14. What is the rate law for the reaction: C 2 4 Br 2 + 3KI => C KBr +KI 3, given the initial rate data below? [C 2 4 Br 2 ], M [KI], M [KI 3 ]/ t (M min -1 ) A. rate = k[ki] B. rate = k[c 2 4 Br 2 ] C. rate = k[ki] 2 D. rate = k[ki][c 2 4 Br 2 ] E. rate = k[ki][c 2 4 Br 2 ] If the half-life of a reactant is independent of its initial concentration, the reaction order is: A. 0 B. 0.5 C. 1 D. 2 E The first order reaction A => products has a half-life of 150 sec. What percent of the sample remains unreacted after 300 sec? A. 25% B. 50% C. 12.5% D. 0.0% E. 100% 17. If a reaction is first order with a rate constant of 5.48 x 10-2 sec -1, how long is required for 3/4 of the initial concentration of reactant to be used up? A sec B sec C. 6.3 sec D sec E sec 18. Which of the following is true for a second order reaction. I. The sum of the exponents in the rate law is equal to two. II. At least one of the exponents in the rate law is a two. III. The half-life is not constant. IV. The half-life is constant. V. The rate constant, k, can be expressed as M -2 s -1 or M -2 min -1.

5 A. I and IV B. II and IV C. I, III, and V D. I and III E. II and III 19. Which statement is NOT correct? A. Activation energy is the same in the forward and reverse direction. B. If the forward reaction is endothermic, the reverse reaction will be exothermic. C. In an endothermic reaction, the activation energy is usually greater than the change in enthalpy. D. An activated complex has higher energy than any molecule contributing to it. E. The activated complex will be the highest on the reaction energy diagram. 20. What is the rate constant at 305 K for the reaction 2N 2 O 5 => 2 N 2 O 4 + O 2, if k = 3.46 x 10-5 s -1 at 298 K and the activation energy, E a = 106 kj/mol? A. 2.4 x 10-5 s -1 B. 4.8 x 10-5 s -1 C. 6.0 x 10-5 s -1 D. 1.2 x 10-5 s -1 E. 9.2 x 10-5 s -1