Syracuse University Project Advance s2

Chemistry 116: General Chemistry Syracuse University Project Advance Exam #2, Spring 2005

Name Date

-7 -11 (1) Carbonic acid is a diprotic acid, H2CO3, with Ka1 = 4.2 x 10 and Ka2 = 4.8 x 10 . The ion -14 product for water is Kw = 1.0 x 10 .

What is the equilibrium constant for the following carbonic acid reaction?

+ 2- H2CO3 + 2H2O 2H3O + CO3

(a) 2.1 x 10-4 (b) 2.0 x 10-17 (c) 4.2 x 10-7 (d) 4.8 x 10-11 (e) 2.4 x 10-8

(2) Label in order, left to right, the Bronsted Lowrey acids and bases in the following reaction:

- 2- + NH3 + HSO4 SO4 + NH4

(a) acid, base, base, acid (b) base, acid, base, acid (c) base, acid, acid, base (d) acid, base, acid, base (e) none of the above

+ (3) What is the concentration of H3O in a solution of 0.075M KOH at 25°C?

(a) 0.075M (b) 0.150M (c) 1.33 x 10-13M (d) 6.66 x 10-14M (e) none of the above

- (4) What is the concentration of OH in a 1.0M solution of aniline, C6H5NH2? -10 (Kb = 4.2 x 10 )

(a) 2.0 x 10-5M (b) 2.0 x 10-6 (c) 4.2 x 10-5M (d) 4.2 x 10-6 M (e) none of the above

(5) What is the minimum concentration of Mg2+ that is needed to begin the formation of a precipitate of Mg(OH)2 in an aqueous solution of pH = 10.0?

CHE 116 1 Spring 2005 Exam #2 -12 (Ksp of Mg(OH)2 equals 6 x 10 ).

(a) 3 x 10-8M (b) 3 x 10-4 (c) 1.5 x 10-4M (d) 6 x 10-8M (e) 6 x 10-4M

(6) Which of the following is a weak electrolyte in aqueous solution?

(a) H2SO4 (b) KOH (c) NH3 (d) NaClO4 (e) HI

(7) A saturated solution of PbBr2 is prepared by dissolving the solid salt in water. The 2+ concentration of Pb in solution is found to be 0.0115 M. The Ksp for PbBr2 is

(a) 4.9 x 10-5 (b) 2.3 x 10-2 (c) 1.2 x 10-5 (d) 6.1 x 10-6 (e) 2.6 x 10-4

(8) A 0.010 M aqueous solution of a weak acid HX has a pH of 4.00. What is the percentage dissociation of HX in the solution?

(a) 0.010% (b) 10% (c) 0.10% (d) 0.0010% (e) 1.0%

(9) The solubility of PbSO4 is 0.041 g/L. Its molar mass is 303 g/mol. Its Ksp is

(a) 1.3 x 10-4 (b) 8.8 x 10-12 (c) 1.7 x 10-3 (d) 4.1 x 10-2 (e) 1.7 x 10-8

(10) Which of the following statements is/are correct?

1. The pH of a vinegar (acetic acid) solution at 25°C is greater than 7.0. CHE 116 2 Spring 2005 Exam #2 2. The hydroxide ion concentration of a 0.35M solution of Ba(OH)2 is 0.70M. 3. The hydroxide ion concentration of a 2.5M solution of HCl at 25°C is 4.0 x 10-15M.

(a) 1 (b) 2 (c) 1 and 2 (d) 1 and 3 (e) 2 and 3

1. In the following reaction, CN- acts as a Lewis base: 3+ - 3- Fe + 6CN  [Fe(CN)6]

2. In the following proton-transfer reaction, Bronsted-Lowrey acids and bases are correctly labeled: 2- + - HPO4 + NH4 H2PO4 + NH3 acid base acid base - + 3. In the following reaction, HSO3 and NH4 are a Bronsted-Lowrey conjugate acid-base 2- + - pair: SO3 and NH4 HSO3 + NH3

(a) 1 (b) 2 (c) 3 (d) 1 and 2 (e) 2 and 3

+ (12) What is the concentration of the conjugate acid, C6H5NH3 , in a 1.0M aqueous solution of the -10 weak base aniline, C6H5NH2? Kb = 4.2 x 10

(a) 4.2 x 10-5M (b) 2.0 x 10-5M (c) 2.0 x 10-10M (d) 4.2 x 10-10M (e) none of the above

1. An aqueous solution of BaClO4 is basic. 2. An aqueous solution of NH4I is acidic. 3. An aqueous solution of KC2H3O2 (potassium acetate) is acidic.

(a) 1 (b) 2 (c) 3 (d) 1 and 2 (e) 2 and 3 (14) The solubility product constant for Iron(III) hydroxide, Fe(OH)3, in pure water at 25°C is Ksp -39 = 2.5 x 10 . Calculate the molar solubility of Fe(OH)3 in pure water (Set-up only).

CHE 116 3 Spring 2005 Exam #2 2 . 5 x 1 0 3 9 (a) 2 2 7

2 . 5 x 1 0 3 9 (b) 3  2 7

2 . 5 x 1 0 3 9 (c) 4  2 7

(c) 2 2.5x10 39  (e) 4 2.5x10 39 

+ - (15) H2SO3(aq) + H2O(l) H3O (aq) + HSO3 (aq)  - + 2- HSO3 (aq) + H2O(l) H3O (aq) + SO3 (aq)

In the above reversible reactions, which are the Bronsted acids?

- 2- (a) HSO3 , H2O, SO3 + - (b) H2O, H3O , HSO3 - (c) H2SO3, H2O, HSO3 + -2 (d) H3O , H2O, SO3 + - (e) H2SO3, H3O , HSO3

(16) Calculate the pH of a 0.017 M Ba(OH)2 solution.

(a) 12.13 (b) 0.034 (c) 1.77 (d) 12.53 (e) 1.47

(17) The ionization constant of water at 45°C is 4.0 x 10-14. What is the pH of pure water at this temperature?

+ - H2O H (aq) + OH (aq)

(a) 7.00 (b) 6.70 (c) 13.40 (d) 5.70 (e) 7.70

(18) The pH of a 0.10 M NH4Cl solution is 5.13. The hydroxide-ion concentration of this solution is

(a) 1.0 x 10-13 M (b) 1.3 x 10-9 M CHE 116 4 Spring 2005 Exam #2 (c) 7.4 x 10-6 M (d) 1.3 x 10-5 M (e) none of these.

(19) A solution that is formed by combining 700 mL of 0.20 M HCl with 300 mL of 0.50 M NaOH + has an H3O concentration of

(a) 1 x 10-12 (b) 0.2 (c) 0.01 (d) 0.02 (e) 0.14

(20) Calculate the pH of a solution prepared by dissolving 0.37 moles of formic acid (HCO2H) and -4 0.23 moles of sodium formate (NaCO2H) in 1.00 L of solution. (Ka = 1.8 x 10 )

(a) 2.09 (b) 10.46 (c) 3.54 (d) 2.30 (e) none of the above

-4 (21) Determine the pH of a 0.15 M solution of KF. Ka = 7.0 x 10 ).

(a) 12.01 (b) 5.83 (c) 8.17 (d) 2.33 (e) 3.46

(22) Which one of the following has the lowest ionization energy? A) iodine B) bromine C) chlorine D) fluorine E) oxygen

(23) In the Periodic Table of the Elements, all the elements in Group 16 have the same number of

(a) valence electrons (b) energy levels (c) protons (d) neutrons (e) orbitals

(24) Nonmetals in the solid state are poor conductors of heat and tend to

(a) be brittle (b) be malleable (c) have luster (d) have good electrical conductivity CHE 116 5 Spring 2005 Exam #2 (f) all of the above

(25) Which element in Group 15 has the most metallic character?

(a) N (b) P (c) As (d) Bi

CHE 116 6 Spring 2005 Exam #2