AP Chemsitry Name :
Worksheet : Test Review Date :
_____ 1. Of the following substances, an aqueous solution of ______will form basic solutions.
NH4Cl Cu(NO3)2 K2CO3 NaF
a) NH4Cl, Cu(NO3)2
b) K2CO3, NH4Cl
c) NaF only
d) NaF, K2CO3
e) NH4Cl only
_____ 2. Of the compounds below, a 0.1-M aqueous solution of ______will have the highest pH.
a) KCN, Ka of HCN = 4.0 x 10-10
b) NH4NO3, Kb of NH3 = 1.8 x 10-5
c) NaOAc, Ka of HOAc = 1.8 x 10-5 (Ac = acetate ion)
d) NaClO, Ka of HClO = 3.2 x 10-8
e) NaHS, Kb of HS- = 1.8 x 10-7
_____ 3. A 0.1-M solution of ______has a pH of 7.0.
a) Na2S
b) KF
c) NaNO3
d) NH4Cl
e) NaF
_____ 4. Of the following, which is the strongest acid?
a) HIO
b) HIO4
c) HIO2
d) HIO3
e) The acid strength of all of the above is nearly the same.
_____ 5. Of the following, the acid strength of ______is the greatest.
a) CH3COOH
b) ClCH2COOH
c) Cl2CHCOOH
d) Cl3CCOOH
e) BrCH2COOH
_____ 6. Of the following, ______is the strongest acid.
a) Cl3-COOH
b) H3C-COOH
c) Br3C-COOH
d) F3C-COOH
e) Br2ClC-COOH
7. Arrange the following 0.10 M solutions in order from most acidic to most basic.
KOH, KC1, KCN, NH4C1, HC1
8. Given that the Ka value for acetic acid is 1.8 x 10-5 and the Ka value for hypochlorous acid is 3.5 x 10-8, which is the stronger base, OC1- or C2H3O2-?
9. Sodium azide (NaN3) is sometimes added to water to kill bacteria. Calculate the concentration of all species in a 0.010 M solution of NaN3. The Ka value for hydrazoic acid (HN3) is 1.9 x 10-5.
10. Calculate the pH of each of the following solutions.
a. 0.10MCH3NH3C1(KbCH3NH2 = 4.38 x 10–4)
b. 0.050 M NaCN (KaHCN = 6.2 x 10–10)
11. An unknown salt is either NaCN(KaHCN = 6.2 x 10–10), NaC2H3O2(KaHC2H3O2 = 1.8 x 10–5), NaF(KaHF = 7.2 x 10–4), NaCl, or NaOCl(KaHOCl = 3.5 x 10–8). When 0.100 mol of the salt is dissolved in 1.00 L of water, the pH of the solution is 8.07. What is the identity of the salt?
12. Calculate the pH of a 0.050 M A1(NO3)3 solution. The Ka value for A1(H2O)63+ is 1.4 x 10-5.
13. Are solutions of the following salts acidic, basic, or neutral? For those which are not neutral, write balanced chemical equations for the reactions causing the solution to be acidic or basic.
a. NaNO3
b. NaNO2 (KaHNO2 = 4.0 x 10–4)
c. NH4NO3 (KbNH3 = 1.8 x 10–5)
d. NH4NO2
e. NaOCl(KaHOCl = 3.5 x 10–8)
f. NH4OC1
14. Place the species in each of the following groups in order of increasing acid strength. Explain the order you chose for each group.
a. HBrO, HBrO2, HBrO3
b. HC1O2, HBrO2, HIO2
15. Place the species in each of the following groups in order of increasing acid strength. Give reasons for the orders you chose.
a. H2O, H2S, H2Se (bond energies: H—O, 467 kJ/mol; H—S, 363 kJ/mol; H—Se, 276 kJ/mol)
b. CH3CO2H, FCH2CO2H, F2CHCO2H, F3CCO2H
c. NH4+, HONH3 +
16. Will the following oxides give acidic, basic, or neutral solutions when dissolved in water? Write reactions to justify your answers.
a. CaO
b. SO2
c. C12O
17. Identify the Lewis acid and the Lewis base in each of the following reactions.
a. B(OH)3 + H2O ↔ B(OH)4- + H+
b. Ag+ + 2NH3 ↔Ag(NH3)2+
c. BF3 + NH3 ↔ F3BNH3
18. Aluminum hydroxide is an amphoteric substance. It can act as either a Brönsted-Lowry base or a Lewis acid. Write a reaction showing A1(OH)3 acting as a base toward H+ and as an acid toward OH-.
19. Would you expect Fe3+ or Fe2+ to be the stronger Lewis acid? Explain.
20. Derive an expression for the relationship between pKa and for a conjugate acid-base pair. (pK = -log K.)
21. At 25°C, a saturated solution of benzoic acid (C6H5CO2H, Ka = 6.4 x 10-5)has a pH of 2.80. Calculate the water solubility of benzoic acid in moles per liter.
22. Codeine is a derivative of morphine that is used as an analgesic, narcotic, or antitussive. It was once commonly used in cough syrups but is now available only by prescription because of its addictive properties. The formula for codeine is C18H21NO3, and the pKb is 6.05. Calculate the pH of a 10.0 mL solution containing 5.0 mg codeine. (pKb = -log Kb.)
23. A 0.050 M solution of the salt NaB has a pH of 9.00. Calculate the pH of a 0.010 M solution of HB.
24. Rank the following 0.10 M solutions in order of increasing pH:
a. HI, HF, NaF, Nal
b. NH4NO3, NaNO3, NaOH, HF, KF, NH3, HNO3
25. Is an aqueous solution of NaHSO4 acidic, basic, or neutral? What reaction occurs with water? Calculate the pH of a 0.10 M solution of NaHSO4.(Ka = 1.2 x 10-2)
26. Calculate [CO32-] in a 0.010 M solution of CO2 in water (H2CO3). If all the CO32- in this solution comes from the reaction HCO3- ↔ H+ + CO32- , what percent of the H+ ions in the solution are a result of the dissociation of HCO3-? (Ka1 = 4.3 x 10-7 ; Ka2 = 5.6 x 10-11)
When acid is added to a solution of sodium hydrogen carbonate (NaHCO3), vigorous bubbling occurs. How is this reaction related to the existence of carbonic acid (H2CO3) molecules in aqueous solution?
27. Calculate the value for the equilibrium constant for each of the following reactions.
a. NH3 + H3O+ ↔ NH4+ + H2O (KbNH3 = 1.8 x 10–5)
b. NO2- + H3O+ ↔ HNO2 + H2O (KaHNO2 = 4.0 x 10–4)
28. Calculate [OH-] in a solution obtained by adding 0.0100 mol of solid NaOH to 1.00 L of 15.0 M NH3. (KbNH3 = 1.8 x 10-5)
29. Phosphoric acid is a common ingredient in traditional cola drinks. It is added to provide the drinks with a pleasantly tart taste. Although phosphoric acid is a triprotic acid, its protons are lost one at a time. Assuming that in cola drinks the concentration of phosphoric acid is 0.007 M, calculate the pH in this solution.( For H3PO4, Ka1 = 7.5 x 10-3)
30. Consider the species PO43-, HPO42-, and H2PO4-. Each ion can act as a base in water. Determine the Kb value for each of these species. Which species is the strongest base?( For H3PO4, Ka1 = 7.5 x 10-3, Ka2 = 6.2 x 10-8, Ka3 = 4.8 x 10-13)
Answers : 7. HCl > NH4C l> KCl KCN KOH 8. OCl- 9. [HN3] = [OH-] = 2.3 x 10-6, [Na+] = 0.010M, [N3-] = 0.010M 10a. pH = 5.82 10b. pH = 10.95 11. Kb = 1.4 x 10-11, Ka therefore = 7.1 x 10-4, which is the Ka for HF, so the salt is NaF 12. pH = 3.08 13. acidic : c and d basic : b, e, and f neutral : a 14a. HBrO < HBrO2 < HBrO3 no. of oxygen atoms increases 14b. HIO2 HBrO2 HC1O2 , electronegativity of central atom increases 15a. H2O < H2S < H2Se as strength of H-X decreases, acid strength increases 15b. CH3CO2H < FCH2CO2H < F2CHCO2H < F3CCO2H electronegativity increases 15c. . NH4+ < HONH3 + electronegativity increases 16a. Basic : CaO + H2O à Ca(OH) 2 16b. acidic : SO2 + H2O à H2SO3 16c. acidic : Cl2O + H2O à 2 HOCl 17. Lewis acids : a. B(OH)3 b. Ag+ c. BF3 Lewis bases : a. H2O b. NH3 c. NH3 18. Al(OH)3 + 3H+ à Al3+ + 3 H2O ; Al(OH)3 + OH- à Al(OH)4- 19. Fe3+ - greater positive charge 20. pKa + pKb = pKw 21. 4.2 x 10-2 M 22. pH = 9.59 23. pH = 3.66 24a. HI < HF < NaI < NaF 24b. HNO3 < HF < NH4NO3 < NaNO3 < KF < NH3 < NaOH 25. acidic : HSO4- ↔ H+ + SO42- ; pH = 1.54 26. [CO32-] = 5.6 x 10-11; [H+] from second dissociation = 8.5 x 10-5 % 27a. 1.8 x 109 27b. 2.5 x 103 28. [OH-] = 0.022 M 29. pH = 2.4 30. Kb for PO43- (strongest base) = 0.021 ; Kb for HPO42-= 1.6 x 10-7, and Kb for H2PO4- = 1.3 x 10-12