# ap ch. 14-15 acids & bases review answers

Post on 23-Nov-2014

99 views

Category:

## Documents

1 download

Tags:

• #### d bcl3 e h

Embed Size (px)

TRANSCRIPT

Ch. 14-15: Acids, Bases and Solubility AP Review Questions **On AP test, if in doubt use 3 significant digits. It is always correct. **For logs: If Ka = 1.8 X10-5, then pKa = 4.7932685. Ka has two significant digits. pKa should be 4.79, since the 4 tells the power (the 7,9 are significant.) ** For strong acids: #Oxygens - # Hydrogens is 2 or greater. H2SO4 strong, H2SO3 weak, HIO3 strong etc. ** Acid strength increases with the number of oxygens. (The more oxygens, the better the negative charge can be supported and be made stable when the H+ leaves.) **Molarity = mol / L = mmol / ml ** For buffer solutions the weak acid must have a pKa within one pH unit of the desired buffer pH. **In titrations: At the halfway point to equivalency HA will equal AHA + OH- H2O + A 1.0M 0.5M -0.5 -0.5 +0.5 0.5 0.5 pH = pKa + log {[A-] / [HA]} pH = pKa At the equivalence point: for strong acids: the titration curve is steep and the equivalence point equals pH = 7. (strong acids and strong bases completely neutralize one another to make a neutral pH of 7.) but for weak acids/weak bases: the titration curve has less of a steepness (it is flatter) and the equivalence point is determined by stoichiometry and the dissociation of the weak acid/ weak base, not by pH. It will not be neutral! (see textbook p. 696-716) {The pH at the equivalence point of a weak acid with a strong base is always greater than 7, because the anion of the acid (that is left in solution) is a base. The weaker the acid, the higher the pH at the equivalence point. The pH at the equivalence point of a weak base with a strong acid will be less than 7, since the hydrated base is acidic. The weaker the base, the lower the pH at the equivalence point.}

1) Which pair of substances cannot be the major components of (coexist in) an aqueous solution? a) OH- and H+ b) H2PO4- and HPO42c) HOCl and OCl d) SO42- and SO32e) H2CO3 and CO32-

4) Which of the following is not a conjugate acidbase pair? a) H2SO4 and SO42b) HCl and Clc) NH3 and NH2d) HPO42- and PO43e) H2S and HS-

5) Which of the following is a Lewis Theory Acid? a) NH3 b) CO2 c) CH4 d) BH3 e) LiH

2) Each of the following can act as both a Bronsted acid and a Bronsted base EXCEPT a) HSO4- b) H2PO4- c) NH4+ d) H2O e) HCO3-

6) Which of the following can function as both a Bronsted-Lowry acid and a Bronsted-Lowry base? a) HCl b) H2SO4 c) HSO3- d) SO42- e) H+

7) In the reaction CO32- + H2O HCO3- + OHthe carbonate ion is a a) Bronsted acid b) Lewis acid c) Arrhenius acid d) Bronsted base e) Arrhenius base

3) Which of the following anion(s) is/are not derived from a strong acid? I. F1II. NO31III. HS-1 1IV. ClO4 V. C2H3O21a) V only b) I, II, and III only c) I, II, and IV only d) I, III, V only e) II and IV only

8) Which of the following is the strongest acid in water? a) perchloric acid b) chloric acid c) chlorous acid d) hypochlorous acid e) They are all the same strength.

Questions 12-13 a) Lithium b) Nickel c) Bromine d) Uranium e) Fluorine 9) When equal masses of the following compounds are dissolved in water, which is expected to conduct electricity the most? a) MgCl2 b) CH3CH2CH2OH c) SO3 d) KMnO4 e) HCO2H 12) Is a gas in its standard state at 298 K. 13) Reacts with water to form a strong base.

14) Which of the following pairs would make an effective buffer solution? a) HCl / NaCl b) KOH / K2SO4 c) HClO4 / NaClO4 d) NaHCO3 / Na2CO3 e) HCl / NH4Cl 10) In aqueous solution the strongest acid is a) HCl b) H3O+ c) HBr d) HI e) All are equally strong.

11) The strongest acid below is a) HClO2 b) HBrO3 c)HClO3 d) H2SO3 e) H2SeO3

15) In aqueous solution the amphiprotic (amphoteric) substance is a) H2O b) Cl- c) NH4+ d) Cr2O72e) CH3CH2COOH

18) Which of the following cannot be a Lewis acid? a) Fe2+ b) Fe3+ c) NH4+ d) BCl3 e) H+

16) Addition of a base to this compound produces a gas. a) CaCO3 b) ZnS c) NH4Br d) CH3COOH e) Mg

17) The strongest base is a) NaClO b) NaClO3 c) NaBrO3 d) KClO3 e) KClO4

Questions 19-22 a) A solution with a pH of 1 b) A solution with a pH of greater than 1 and less than 7 c) A solution with a pH of 7 d) A solution with a pH of greater than 7 and less than 13 e) A solution with a pH of 13 For CH3COOH, Ka = 1.8 X10-5 For NH3, Kb = 1.8 X10-5 19) A solution prepared by mixing equal volumes of 0.2 molar HCl and 0.2 molar NH3. 20) A solution prepared by mixing equal volumes of 0.2 molar HNO3 and 0.2 molar NaOH. 21) A solution prepared by mixing equal volumes of 0.2 molar HCl and 0.2 molar NaCl. 22) A solution prepared by mixing equal volumes of 0.2 molar CH3COOH and 0.2 molar NaOH.

Questions 23-25 refer to an experiment in which five individual 1-liter aqueous solutions, each containing a 1 mole sample of one of the salts listed below, were subjected to various tests at room temperature. a) NaC2H3O2 b) NaCl c) MgBr2 d) HC2H3O2 e) KBr 23) The solution containing this salt had the highest boiling point. 24) The solution containing this salt had the lowest conductivity. 25) The solution containing this salt had the highest pH.

Use the following responses for questions 26-28. a) HOCl Ka = 3.0 X10-8 b) HC2H3O2 Ka = 1.8 X10-5 c) N2H4 Kb = 9.6 X10-7 d) HNO2 Ka = 7.1 X10-4 e) CH3NH2 Kb = 4.4 X10-4 26) A 0.01 M solution of this substance will result in a solution with the highest pH. 27) A 0.1 M solution of the sodium salt of this substance will have a pH closest to pH 7. 28) This substance is most often found in salad dressing.

Questions 31-33 a) Arrhenius acid b) Bronsted-Lowry acid c) Bronsted-Lowry base d) Lewis acid e) Lewis base 31) BF3 in the reaction: BF3 + F- BF4 32) CN- in the reaction: Cu2+(aq) + 4 CN-(aq) Cu(CN)42-(aq) 33) H2O in the reaction: HC2H3O2(aq) + H2O(l) C2H3O2-(aq) + H3O+(aq)

29) Each of the following compounds was added to distilled water at 25 oC. Which one produced a solution with a pH that was less than 7? a) N2 b) O2 c) NaI d) MgO e) SO2

34) Which substance(s) listed below would form basic solutions? I. NH4Cl II. K2CO3 III. NaF a) I only b) II only c) III only d) I and II e) II and III

30) In which of the following reactions does the H2PO4- ion act as an acid? I. H3PO4 + H2O H3O+ + H2PO4II. H2PO4- + H2O H3O+ + HPO42III. H2PO4- + OH- H3PO4 + O2a) I only b) II only c) III only d) I and II e) I and III

Questions 35-36 Acid a) HC2H3O2 b) HCN c) HNO2 d) HCHO2 e) HOBr

Acid dissociation constant 1.8 X10-5 6.2 X10-10 7.1 X10-4 1.8 X10-4 2.1 X10-9

35) When each of these acids is titrated, which one will have the highest pH at its endpoint? 36) Which of these five acids and their corresponding salts can be used to make a buffer at pH 6.5? a) HC2H3O2 b) HC2H3O2 or HOBr c) HC2H3O2 and HNO2 and HCHO2 d) HOBr e) none of these

37) Which of the following is the safest and most effective procedure to treat a base spill onto skin? a) Dry the affected area with paper towels. b) Flush the area with a dilute solution of HCl. c) Flush the affected area with water and then with a dilute NaOH solution. d) Flush the affected area with water and then with a dilute NaHCO3 solution. e) Flush the affected area with water and then with a dilute vinegar solution.

38) Acid precipitation or acid rain has a pH below the normal value for rainwater. Normal rain has a pH between 5 and 6. Which of the following are contributors to acid precipitation? I. O3 II. N2 III. NO IV. SO2 V. O2 VI. SO3 a) I and III only b) III, IV, and VI only c) III and VI only d) I, II, and V only e) IV and VI only

39) The safest and most effective emergency procedure to treat an acid splash on skin is to do which of the following immediately? a) Dry the affected area with paper towels. b) Sprinkle the affected area with powdered Na2SO4(s). c) Flush the affected area with water and then with a dilute NaOH solution. d) Flush the affected area with water and then with a dilute NaHCO3 solution. e) Flush the affected area with water and then with a dilute vinegar solution.

40) A solution of KNO3 is known to have a concentration of 0.564 m. In order to calculate the concentration of this solution in terms of molarity, which of the following needs to be specified? a) no additional information b) the density of the solution c) the volume of the solution d) the solubility product of KNO3 e) the Ka of nitric acid

41) Which of the following equilibrium expressions represents the hydrolysis of the CNion? a) K = {[HCN][OH-]} / [CN-] b) K = {[CN-][OH-]} / [HCN] c) K = {[CN-][H3O+]} / [HCN] d) K = {[HCN][H3O+]} / [CN-] e) K = [HCN] / {[CN-][OH-]}

44) A 40.0 ml sample of 0.25 M KOH is added to 60.0 ml of 0.15 M Ba(OH)2. What is the molar concentration of OH-(aq) in the resulting solution? (Assume that the volumes are additive.) a) 0.10 M b) 0.19 M c) 0.28 M d) 0.40 M e) 0.55 M

42) 50.0 ml of a 0.0200 M HCl solution is mixed with 25.0 ml of a 0.0100 M NaOH solution. What is the pH of the final mixture? a) 3.36 b) 0.43 c) 2.00 d) 11.00 e) 7.00

43) How many milliliters of water must be added to 10 milliliters of an HCl solution with a pH of 1 to produce a solution with a pH of 2? a) 10 ml b) 90 ml c) 100 ml d) 990 ml e) 1000 ml

45) A 0.010 M solution of a weak base has a pH of 9.85. What is the pKb of this weak base? a) 4.15 b) 7.1 X10-5 c) 2.0 X10-7 d) 7.85 e) 6.30

46) Phosphoric acid dissociates in three steps with equilibrium constants K1 = 7.1 X10-3 K2 = 6.3 X10-8 K3 = 4.5 X10-13 Which of the following mathematical expressions represents the pH of a 0.100 M solution of K2HPO4? a) log K1 b) log [(7.1 X10-3)(6.3 X10-8)] c) log K2 d) log [(K2)(K3)] e) 7.00

47) What is the H+(aq) concentration in 0.05 M HCN(aq)? ( The Ka for HCN is 5.0 X10-10.) a) 2.5 X 10-11 M b) 2.5 X 10-10 M c) 5.0 X 10-10 M d) 5.0 X 10-6 M e) 5.0 X 10-4 M

48) Hypobromous acid, HBrO, is added to di

Recommended