REVIEW EXAM 1 CHAP 11 &12

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1 REVIEW EXAM 1 CHAP 11 &12 1.In a 0.1 molar solution of NaCl in water, which one of the following will be closest to 0.1? A) The mole fraction of NaCl. B) The mass fraction of NaCl. C) The mass percent of NaCl. D) The molality of NaC. E) All of these are about A liquid-liquid solution is called an ideal solution if: I. It obeys PV = nrt. II. It obeys Raoult's law. III. Solute-solute, solvent-solvent, and solute-solvent interactions are very similar. IV. Solute-solute, solvent-solvent, and solute-solvent interactions are quite different. A) I, II, III B) I, II, IV C) II, III D) II, IV E) I, III, IV 3. If the mole fraction of benzene in a particular benzene-toluene solution is 0.64, what is the mole fraction of benzene in the vapor phase in equilibrium with that solution? A) 0.24 B) 0.50 C) 0.64 D) 0.78 E) When g of NH 4 NO 3 was added to g of water in a Styrofoam cup, the temperature dropped by C. The heat capacity of H 2 O is 4.18 J/g C. Assume the specific heat of the solution equals that of pure H 2 O and that the calorimeter neither absorbs nor leaks heat. The molar heat of solution of solid NH 4 NO 3 is: A) +257 J/mol B) kj/mol C) kj/mol D) 2.57 kj/mol E) 257 J/mol

2 5.The term "proof" is defined as twice the percent by volume of pure ethanol in solution. Thus, a solution that is 95% (by volume) ethanol is 190 proof. What is the molarity of ethanol in a 92 proof ethanol/water solution? density of ethanol = 0.80 g/cm 3 density of water = 1.0 g/cm 3 mol. wt. of ethanol = 46 g/mol A) 0.46 M B) 0.80 M C) 0.92 M D) 8.0 M E) 17 M 6. Which of the following correctly states the relationship between temperature and the solubility of a substance in water? A) The solubility of a substance in water increases as the temperature rises, especially for gases. B) The solubility of a substance in water decreases as the temperature rises, especially for ionic solids. C) The solubility of a substance in water with temperature cannot be accurately predicted, especially for ionic solids. D) The solubility of a substance in water decreases as the temperature lowers, especially for gases. E) Both A and D are correct. 7. hexane (C 6 H 14 ) and octane (C 8 H 18 ) A) relatively ideal B) positive deviation C) negative deviation D) more information needed 8. Determine the mass of a nonvolatile, nonionizing compound that must be added to 3.83 kg of water to lower the freezing point to C. The molar mass of the compound is 50.0 g/mol and the K f for water is 1.86 C kg/mol. A) 203 g B) 134 g C) 463 g D) 9.12 g E) 18.7 g 9. The molar mass of a solid as determined by freezing point depression is 10% higher than the true molar mass. Which of the following experimental errors could not account for this discrepancy? A) Not all the solid was dissolved. B) More than the recorded amount of solvent was pipetted into the solution. C) The solid dissociated slightly into two particles when it dissolved. D) Some solid was left on the weighing paper. E) Before the solution was prepared, the container was rinsed with solvent and not dried.

3 10.In osmosis: A) Knowing the osmotic pressure can help determine the molar mass of a solute dissolved in a solvent. B) The semipermeable membrane is used to change the freezing and melting points of a solution. C) Solutions cannot have identical osmotic pressures. D) Temperature does not affect the osmotic pressure of a solution. E) At least two of the above statements are correct. 11. Consider the reaction What is the ratio of the initial rate of the appearance of water to the initial rate of disappearance of oxygen? A) 1 : 1 B) 2 : 1 C) 1 : 2 D) 2 : 2 E) 3 : Consider the reaction X Y + Z Which of the following is a possible rate law? A) Rate = k[x] B) Rate = k[y] C) Rate = k[y][z] D) Rate = k[x][y] E) Rate = k[z] 13. The reaction of with hydroxide ion proceeds with the formation of. The following data were obtained at 55 C. [(CH 3 ) 3 CBr] 0 [OH ] 0 Initial Rate Exp. (mol/l) (mol/l) (mol/l) ? What will the initial rate (in mol/l s) be in Experiment 4? A) B) C) D)

4 14.Tabulated below are initial rate data for the reaction: 2Fe(CN) I 2Fe(CN) I 2 Run [Fe(CN) 3 6 ] 0 [I ] 0 [Fe(CN) 4 6 ] 0 [I 2 ] 0 Rate (M/s) What is the value of k? A) 10 7 M 5 s 1 B) 10 3 M 3 s 1 C) 10 M 2 s 1 D) 50 M 2 s The reaction 2A + 5B products is second order in A and first order in B. What is the rate law for this reaction? A) rate = k[a] 2 [B] 5 B) rate = k[a] 1 [B] 2 C) rate = k[a] 2 [B] 1 D) rate = k[a] 5 [B] 2 E) rate = k[a] 2/7 [B] 5/7 16. The reaction has the following rate law: After a period of s, the concentration of NO falls from an initial value of mol/l to mol/l. What is the rate constant, k? A) 1.5 B) 5.3 C) 3.2 D) 1.2 E) The rate law for a reaction is found to be Rate = k[a] 2 [B]. Which of the following mechanisms gives this rate law? I. A + B E (fast) E + B C + D (slow) II. A + B E (fast) E + A C + D (slow) III. A + A E (slow). E + B C + D (fast) A) I B) II C) III D) two of these

5 18.Consider the reaction 2O 3 (g) O 3 O 2 + O O 3 + O 2O 2 3O 2 (g). The following mechanism is proposed: If we assume the second step of the mechanism is the rate determining step and the first step is a fast equilibrium step, which of the following rate laws is predicted by this mechanism? A) rate = k[o 3 ] B) rate = k[o 3 ] 2 [O 2 ] C) rate = k[o 3 ] 2 [O 2 ] 1 D) rate = k[o 3 ] The rate constant for a reaction at 40.0 C is exactly 3 times that at 20.0 C. Calculate the Arrhenius energy of activation for the reaction. A) 9.13 kj/mol B) 5.04 kj/mol C) 41.9 kj/mol D) 3.00 kj/mol 20. The dimerization of NO 2 has a rate constant at 25 C of 2.45 x 10-2 L/mol min. What will be the concentration of NO 2 after 120. seconds, given a starting concentration of NO 2 of 11.5 mol/l? A) mol/l B) mol/l C) 7.36 mol/l D) mol/l E) 12.1 mol/l

6 Answers: DCEBDCABCABAACCEBCCC

Useful Information Provided on Exam 1. Sections Covered on Exam , 10.2, 10.8,

Useful Information Provided on Exam 1. Sections Covered on Exam , 10.2, 10.8, Chem 101B Exam 1 Study Questions Name: Chapters 10(partial), 11 & 12(partial) Review Tuesday 2/7/2017 Due on Exam Thursday 2/9/2017 (Exam 1 date) This is a homework assignment. Please show your work for