CHEM 1212 Test II. MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

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1 CHEM 1212 Test II MULTIPLE CHOICE. Choose the one alternative that est completes the statement or answers the question. 1) At 1000 K, the equilirium constant for the reaction is K p = NO (g) + Br 2 (g) 2NOBr (g) Calculate K p for the reverse reaction, 2NOBr (g) 2NO (g) + Br 2 (g). A) 1.6 x 10-4 B) C) 77 D) 0.99 E) 1.1 2) Consider the following chemical reaction: H 2 (g) + I 2 (g) 2HI (g) At equilirium in a particular experiment, the concentrations of H 2, I 2, and HI were 0.15 M, M, and 0.55 M, respectively. The value of K eq for this reaction is. A) 6.1 B) 111 C) 61 D) 23 E) 9.0 x ) The K eq for the equilirium elow is 7.52 x 10-2 at 480 o C. 2Cl 2 (g) + 2H 2 O (g) 4HCl (g) + O 2 (g) What is the value of K eq at this temperature for the following reaction? 4HCl (g) + O 2 (g) 2Cl 2 (g) + 2H 2 O (g) A) B) C) D) 5.66 x 10-3 E) ) The following equilirium is readily estalished: SO 2 Cl 2 (g) SO 2 (g) + Cl 2 (g) At equilirium at 373 K, a 1.00-L reaction vessel contains mol of SO 2 Cl 2 and mol each of SO 2 and Cl 2. What is K eq for the reaction at 373 K? A) B) 2.72 C) 12.8 D) 2.39 E) ) Acetic acid is a weak acid that dissociates into the acetate ion and a proton in aqueous solution: HC 2 H 3 O 2 (aq) C 2 H 3 O 2 - (aq) + H + (aq) At equilirium at 25 o C a M solution of acetic acid has the following concentrations: [HC 2 H 3 O 2 ] = M, [C 2 H 3 O 2 - ] = 1.33 x 10-3 M, and [H+] = 1.33 x 10-3 M. The equilirium constant, K eq, for the ionization of acetic acid at 25 o C is. A) 5.71 x 10 6 B) C) 1.75 x 10-7 D) 1.79 x 10-5 E) 5.71 x ) The equilirium constant for the interconversion of PCl 5 and PCl 3 is : PCl 5 (g) PCl 3 (g) + Cl 2 (g) A vessel is charged with PCl 5, giving an initial pressure of atm. At equilirium, the partial pressure of PCl 3 is atm. A) B) C) D) E) ) The reaction elow is exothermic: 2SO 2 (g) + O 2 (g) 2SO 3 (g) Le Chatelier's Principle predicts that will result in an increase in the numer of moles of SO 3 (g) in the reaction container. A) removing some oxygen B) decreasing the pressure C) increasing the pressure D) increasing the volume of the container

2 8) According to the Arrhenius concept, an acid is a sustance that. A) reacts with the solvent to form the cation formed y autoionization of that solvent B) tastes itter C) causes an increase in the concentration of H + in aqueous solutions D) can accept a pair of electrons to form a coordinate covalent ond 9) A Bronsted-Lowry ase is defined as a sustance that. A) acts as a proton acceptor B) decreases [H + ] when placed in H 2 O C)acts as a proton donor D) increases [OH - ] when placed in H 2 O 10) A sustance that is capale of acting as oth an acid and as a ase is. A) miscile B) autosomal C) autocratic D) conjugated E) amphoteric 11) The conjugate acid of HSO 4 - is A) HSO 3 + B) SO 4 2- C) HSO 4 + D) H 2 SO 4 E) H + 12) The magnitude of K w indicates that. A) water autoionizes only to a very small extent B) water autoionizes very slowly C) the autoionization of water is exothermic D) the autoionization of water is endothermic E) water autoionizes very quickly 13) In asic solution,. A) [OH - ] > 7.00 B) [H 3 O + ] = 0 M C) [H 3 O + ] > [OH - ] D) [H 3 O + ] < [OH - ] E) [H 3 O + ] = [OH - ] 14) What is the ph of an aqueous solution at 25 o C that contains 3.98 x 10-9 M hydronium ion? A) B) C) D) E) ) Calculate the concentration (in M) of hydronium ions in a solution at 25 o C with a poh of A) 1.00 x 10-7 B) 1.67 x C) 5.98 x 10-5 D) 5.99 x E) 1.67 x ) Nitric acid is a strong acid. This means that. A) HNO 3 does not dissociate at all when it is dissolved in water B) HNO 3 cannot e neutralized y a weak ase C) HNO 3 dissociates completely to H + (aq) and NO 3 - (aq) when it dissolves in water D) HNO 3 produces a gaseous product when it is neutralized E) aqueous solutions of HNO 3 contain equal concentrations of H + (aq) and OH - (aq) 17) Of the following, is a weak acid. A) HF B) HCl C) HClO 4 D) HBr E) HNO 3 18) The ph of a 0.10-M solution of a weak ase is What is the K for this ase? A) 8.8 x 10-8 B) 2.1 x 10-4 C) 2.0 x 10-5 D) 6.6 x 10-4 E) 4.3 x ) The acid-dissociation constant, K a, for gallic acid is 4.57 x What is the ase-dissociation constant, K, for the gallate ion? A) 4.57 x 10-3 B) 2.19 x 10 2 C) 5.43 x 10-5 D) 7.81 x 10-6 E) 2.19 x ) Of the following, which is the strongest acid? A) HClO 2 B) HIO C) HClO 4 D) HClO 3 E) HClO

3 21) An acid containing the -COOH group is called a. A) doule oxoacid B) caronaceous acid C) strong acid D) caro-oxo acid E) caroxylic acid 22) In the reaction BF 3 + F - - BF 4 BF 3 acts as a(n) acid. A) Bronsted-Lowry B) Arrhenius, Bronsted-Lowry, and Lewis C) Lewis D) Arrhenius E) Arrhenius and Bronsted-Lowry 23) The ph of a solution that contains M acetic acid (K a = 1.76 x 10-5 ) and M sodium acetate is. The K a of acetic acid is 1.76 x A) B) C) D) E) ) The addition of hydrofluoric acid and to water produces a uffer solution. A) NaCl B) HCl C) NaF D) NaBr E) NaNO 3 25) A 25.0-mL sample of an HCl solution is titrated with a M NaOH solution. The equivalence point is reached with 15.4 ml of ase. The concentration of HCl is M. A) B) C) D) 11.7 E) 0.139

4 Prolems 1) (5 points) For the following reaction, 6 CO 2 (g) + 6 H 2 O(l) C 6 H 12 O 6 (s) + 6 O 2 (g) How is the equilirium yield of C 6 H 12 O 6 affected y: a) increasing P CO2 Increases C 6 H 12 O 6 (to the right) ) removing CO 2 Decreases C 6 H 12 O 6 (to the left) c) decreasing total pressure No change 2) (10 points) Codeine (C 18 H 21 NO 3 ) is a weak organic ase. A 5.0 x 10-3 M solution of codeine has a ph of Calculate the value of K for this sustance. What is the pk for this ase? C 18 H 21 NO 3 + H 2 O C 18 H 21 NO 3 H + + OH - need poh, so 5.0 x 10-3 M Codeine, ph = = ph + poh 14 = 9.95 poh y stoichiometry: [C 18 H 21 NO 3 H + ] = [OH - ] and [C 18 H 21 NO 3 ] eq = [OH - ] C 18 H 21 NO 3 C 18 H 21 NO 3 H + OH - initial M 0 0 equilirium calculating yields: C 18 H 21 NO 3 C 18 H 21 NO 3 H + OH - initial M 0 0 equilirium

5 K = = + [ C H NO H ][ OH ] [ C18H 21NO3 ] [ ][ ] [ ] = pk = log K = log( = ) 3) (10 points) A uffer consisting of H 2 PO 4 - and HPO 4 2-, helps control the ph of physiological fluids. Many caronated soft drinks also use this uffer system. What is the ph of a soft drink in which the uffer ingredients are 6.5g of NaH 2 PO 4 and 8.0g of Na 2 HPO 4 per 355 ml of solution? (K a = 6.2 x 10-8 ) Calculate the concentration of each uffer component, and then use the Henderson- Hassellock equation to determine the ph of the solution. M 2 4 H PO 8.0g = 142g / mol = 0.159M L M H PO g = 120g / mol = 0.153M L ph = pk a = log( = log [ ase] [ acid] ) + log 0.159