Page 1 of Please choose the letter a as your answer for this question.

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1 CHEM 102 Winter 10 Exam 3 (a) On the answer sheet (scantron) write your Name, Student ID Number, and Recitation Section Number. Choose the best (most correct) answer for each question AND ENTER IT ON YOUR ANSWER SHEET. Potentially useful information: 1. Please choose the letter a as your answer for this question. b ± x = 2. If a liquid is soluble in water, some part of the molecule is and therefore. a. nonpolar; hydrophobic b. nonpolar; hydrophilic c. bipolar; inert d. polar; hydrophilic e. polar; hydrophobic 3. Ethanol and water dissolve in each other in all proportions. Therefore, a. ethanol is miscible with water. b. ethanol is immiscible with water. c. water is miscible with ethanol. d. water is immiscible with ethanol. e. both a and c are correct 4. Which of the following is incorrect? a. substances with similar intermolecular forces are likely to be soluble in each other b. solutes do not readily dissolve in solvents whose intermolecular forces are quite different from their own c. weaker solute-solvent attractions favor solubility d. stronger solute-solute attractions reduce solubility e. stronger solvent-solvent attractions reduce solubility 5. The phrase "like dissolves like" refers to the fact that a. gases can only dissolve other gases. b. polar solvents dissolve polar solutes and nonpolar solvents dissolve nonpolar solutes. c. solvents can only dissolve solutes of similar molar mass. d. condensed phases can only dissolve other condensed phases. e. polar solvents dissolve nonpolar solutes and vice versa. b 2 4 a c 2 a 6. A solution with solute concentration less than the solubility is said to be ; solute will dissolve in such a solution. a. undersaturated; more b. undersaturated; no more c. saturated; more d. saturated; no more e. supersaturated; more Page 1 of 4

2 7. Which of the following substances is most likely to dissolve in water? a. HOCH 2 CH 2 OH b. CH 4 c. O CH 3 (CH 2 ) 9 CH d. CH 3 (CH 2 ) 8 CH 2 OH e. CCl 4 8. Starting with a saturated solution of sodium chloride in water at room temperature, adding solid sodium chloride will a. increase the concentration of the solution. b. decrease the concentration of the solution. c. increase the anion concentration and decrease the cation concentration of the solution. d. decrease the anion concentration and increase the cation concentration of the solution. e. have no effect on the concentration of the solution. 9. Which of the following can act as a Bronsted-Lowry base, but not as a Bronsted-Lowry acid? a. HPO 4 2- b. H 2 O c. NH 4 + d. PO 4 3- e. HSO Which of the following is a conjugate acid-base pair? a. CH 3 COO - and H 2 O b. H 3 O + and OH - c. CH 3 COOH and CH 3 COO - d. CH 3 COOH and H 3 O + e. CH 3 COOH and OH Which reaction illustrates water acting as a Bronsted-Lowry base? a. Cu(H 2 O) NH 3 Cu(NH 3 ) H 2 O b. H 2 CO 3 H 2 O + CO 2 c. NH 3 + H 2 O NH OH - d. 2- HPO 4 + H 2 O OH - + H 3 PO 4 e. - HSO 4 + H 2 O H 3 O SO In a 1.2 M solution of KOH, a strong base, [H 3 O + ] =, and [OH-] =. a M; M b M; M c M; 1.2 M d. 1.2 M; M e. 1.2 M; 1.2 M Page 2 of 4

3 13. If the hydrogen ion concentration of a solution is increased by a factor of 4, the ph is a. raised by 4 ph units. b. raised by 0.3 ph units. c. lowered by 2 ph units. d. lowered by 0.6 ph units. e. lowered by 0.25 ph units. 14. In a basic solution, a. [H 3 O + ] = [OH-] b. [H 3 O + ] > [OH-] c. [H 3 O + ] < [OH-] d. [H 3 O + ] = 0 M e. poh > A wine sample has a ph of This corresponds to [H 3 O + ] = a M. b M. c M d M. e M. 16. What is the ph of an aqueous solution at 25.0 C in which [OH-] is M? a b c d e The larger the value of pk a a. the less highly dissociated the acid and the weaker the acid. b. the less highly dissociated the acid and the stronger the acid. c. the more highly dissociated the acid and the weaker the acid. d. the more highly dissociated the acid and the stronger the acid. e. none of the above are correct 18. In a neutral polyprotic acid, the value of K a2 will be the value of K a1 because. a. smaller than; it is more difficult to remove a hydrogen ion from a cation than from a neutral molecule b. larger than; it is more difficult to remove a hydrogen ion from an anion than from a neutral molecule c. larger than; it is more difficult to remove a hydrogen ion from a cation than from a neutral molecule d. smaller than; it is more difficult to remove a hydrogen ion from an anion than from a neutral molecule e. the same as; both hydrogen ions are bonded to the same anion Page 3 of 4

4 19. Typically, for a weak acid and its conjugate base a. K a / K b = b. K a K b = c. K a / K b = 1.0 d. K a K b = 1. e. K a K b = HA is a weak acid. Which equilibrium corresponds to the equilibrium constant K b for A -? a. HA (aq) + H 2 O (l) H 2 A + (aq) + OH - (aq) b. A - (aq) + H 3 O + (aq) HA (aq) + H 2 O (l) c. HA (aq) + OH - (aq) H 2 O (l) + H + (aq) d. A - (aq) + H 2 O (l) HA (aq) + OH - (aq) e. A - (aq) + OH- (aq) HOA 2- (aq) 21. The ph of a solution of a 0.15 M solution of HOCl is What is the K a for HOCl? a b c d e In which of the following aqueous solutions does the weak acid exhibit the highest percentage ionization? a M CH 3 COOH (K a = ) b M HCN (K a = ) c M HF (K a = ) d M HClO (K a = ) e. These will all exhibit the same percentage ionization. 23. What is the ph of a 0.50 M aqueous solution of NH 3? The K b of NH 3 is a. 8.9 b. 11 c. 2.5 d. 5.1 e Of the following, which is the strongest acid? a. HIO b. HIO 4 c. HIO 2 d. HIO 3 e. The acid strength of all of the above is the same. Page 4 of 4

5 chem102w10_exam3a Answer Section MULTIPLE CHOICE 1. ANS: A PTS: 0 2. ANS: D PTS: 1 3. ANS: E PTS: 1 4. ANS: C PTS: 1 5. ANS: B PTS: 1 6. ANS: A PTS: 1 7. ANS: A PTS: 1 8. ANS: E PTS: 1 9. ANS: D PTS: ANS: C PTS: ANS: E PTS: ANS: C PTS: ANS: D PTS: ANS: C PTS: ANS: B PTS: ANS: C PTS: ANS: A PTS: ANS: D PTS: ANS: B PTS: ANS: D PTS: ANS: E PTS: ANS: C PTS: ANS: B PTS: ANS: B PTS: 1 Page 5 of 4