Chapter 5 Acid-Base Equilibrium Part 1 1.Ammonia is a base because: A.When dissolved in water,OH ions are produced B.The nitrogen can donate a lone pair to an acid C.The nitrogen can accept a proton from an acid D.None of the above E.All of the above 2.In an acid-base reaction: A.Water will always act as a base,capturing a proton from the acid B.Water will always act as an acid,giving up a proton to the base C.A proton will be transferred from the acid to the base D.A proton will be transferred from the base to the acid E.Water is always a product of the reaction 3.HCIO2(aq)is a stronger acid than HCIO(aq)because: A.The H atom in HCIO is bound to the Cl atom B.The Cl atom in HCIO2 is more electronegative than that in HCIO C.The extra oxygen atom"pushes"the H atom off of the HCIO2molecule D.The extra oxygen atom pulls bonding electrons towards itself,weakening the O-H bond in HCIOz E.None of the above 4.HBr is a stronger acid than HCI because: A.The Br atom is more electronegative than the Cl atom,making the H-Br bond weaker B.The Cl atom is more electronegative than the Br atom making the H-Cl bond stronger C.The Br atom is larger
Chapter 5 Acid-Base Equilibrium Part 1 1. Ammonia is a base because: A. When dissolved in water, OH- ions are produced B. The nitrogen can donate a lone pair to an acid C. The nitrogen can accept a proton from an acid D. None of the above E.All of the above 2. In an acid-base reaction: A.Water will always act as a base, capturing a proton from the acid B.Water will always act as an acid, giving up a proton to the base C. A proton will be transferred from the acid to the base D. A proton will be transferred from the base to the acid E. Water is always a product of the reaction 3. HClO2(aq) is a stronger acid than HClO(aq) because: A. The H atom in HClO2 is bound to the Cl atom B.The Cl atom in HClO2 is more electronegative than that in HClO C. The extra oxygen atom "pushes" the H atom off of the HClO2 molecule D.The extra oxygen atom pulls bonding electrons towards itself, weakening the O-H bond in HClO2 E. None of the above 4. HBr is a stronger acid than HCl because: A. The Br atom is more electronegative than the Cl atom, making the H-Br bond weaker B.The Cl atom is more electronegative than the Br atom making the H-Cl bond stronger C.The Br atom is larger 1
D.Br-ions are more soluble than Cl-ions E.None of the above 5.Perchloric acid,HCIO4.is a strong acid.Which of the following statements is true? A.Solutions of HCIO will contain insignificant quantities of undissociated HClO4 molecules B.The perchlorate ion,ClO,is a weak base C.Ka of perchloric acid is large D.In an aqueous solution of HCIO4,[H3O][OH-]=Kw E.All of the above 6.Dimethyl amine,(CH3)NH,is a weak base.Which of the following is true? A.Upon addition of a strong acid to aa aqueous solution of dimethylamine,a salt will be produced B.The proton from an acid will be attracted to the lone pair on the N atom of the base C.(CH3)NHz*is a strong acid D.Aqueous solutions of dimethylamine will contain very little(CH3)NH2" E.All of the above 7.For the polyprotic acid HPO dissolved in water: Ka<Ka<Kas A.The predominant species in solution is PO B.The predominant species in solution is HPO C.The solution is acidic mostly due to the hydrolysis of H2PO D.None of the above 8.If NaNOz(s)is added to an aqueous solution of the weak acid HNO2: A.The pH rises B.The pH falls C.The pH is unaffected
D.Br- ions are more soluble than Cl- ions E.None of the above 5. Perchloric acid, HClO4, is a strong acid. Which of the following statements is true? A. Solutions of HClO4 will contain insignificant quantities of undissociated HClO4 molecules B. The perchlorate ion, ClO4 - , is a weak base C. Ka of perchloric acid is large D. In an aqueous solution of HClO4, [H3O+ ][OH-] = Kw E. All of the above 6. Dimethyl amine, (CH3)2NH, is a weak base. Which of the following is true? A. Upon addition of a strong acid to aa aqueous solution of dimethylamine, a salt will be produced B. The proton from an acid will be attracted to the lone pair on the N atom of the base C. (CH3)2NH2 + is a strong acid D.Aqueous solutions of dimethylamine will contain very little (CH3)2NH2 + E. All of the above 7. For the polyprotic acid H3PO4 dissolved in water: Ka1 < Ka2 < Ka3 A. The predominant species in solution is PO4 -3 B. The predominant species in solution is HPO4 -2 C. The solution is acidic mostly due to the hydrolysis of H2PO4 - D. None of the above 8. If NaNO2(s) is added to an aqueous solution of the weak acid HNO2: A. The pH rises B. The pH falls C. The pH is unaffected 2
9.Assume you have a basic buffer system composed of ammonia and ammonium chloride. The Henderson-Hasselbach equation is pH=pKa-log[acid [base]).Here,the acid and base are: A.H:O*and OH' B.H3O*and H2O C.NH;and NH4 D.NH*and NH3 E.NH+and OH 10.CaF2 is a sparingly soluble salt.HF is a weak acid.If the pH of a solution of CaF2 is lowered,the solubility of CaF2 will: A.Increase B.Decrease C.Not change 11.The values of pK(1)and pKa(2)for chromic acid(H2CrO)are 0.74 and 6.49 respectively.(a)Determine values of Ka for each dissociation step.(b)Write equations to represent the dissociation steps of chromic acid in aqueous solution. 12.Four pKa values(1.0,2.7.0,90)are tabulated for the acid HaP2O.Write equations to show the dissociation steps in aqueous solution and assign,with reasoning,a pKa value to each step. 13.The values of pK for CH3CO2H and CF3CO2H are 4.75 and 0.23,both of which are very nearly independent of temperature.Suggest reasons for this difference. 14.Write down expressions for K for the following ionic salts:(a)AgCl:(b)Cac3 (c)CaF2
9. Assume you have a basic buffer system composed of ammonia and ammonium chloride. The Henderson-Hasselbach equation is pH = pKa - log{[acid]/[base]}. Here, the acid and base are: A. H3O+ and OHB. H3O+ and H2O C. NH3 and NH4+ D. NH4 + and NH3 E. NH4+ and OH- 10. CaF2 is a sparingly soluble salt. HF is a weak acid. If the pH of a solution of CaF2 is lowered, the solubility of CaF2 will: A. Increase B. Decrease C. Not change 11. The values of pKa(1) and pKa(2) for chromic acid (H2CrO4) are 0.74 and 6.49 respectively. (a) Determine values of Ka for each dissociation step. (b) Write equations to represent the dissociation steps of chromic acid in aqueous solution. 12. Four pKa values (1.0, 2.0, 7.0, 9.0) are tabulated for the acid H4P2O7. Write equations to show the dissociation steps in aqueous solution and assign, with reasoning, a pKa value to each step. 13. The values of pKa for CH3CO2H and CF3CO2H are 4.75 and 0.23, both of which are very nearly independent of temperature. Suggest reasons for this difference. 14. Write down expressions for Ksp for the following ionic salts: (a) AgCl; (b) CaCO3; (c) CaF2. 3
15.How many chelate rings are present in each of the following complexes?Assume that all the donor atoms are involved in coordination.(a)Cu(trien):(b)[Fe(ox)] (c)[Ru(bpy);(d)[Co(dien)2]; Part2 1.Ammonia is a base because: When dissolved inater.are produced The nitrogen ean donatelone pair toanaci The nitrogen can acceptaproon from a acid None of the above All of the above 2.In an acid-base reaction: Water will alays the acid Water will always act as a aid.giving upa proon to the base proto ill betransferred from the acid to the base Aproto will be transferred from the base to the acid Water iswaysaproductftheeaction 3.HClO is a stronger acid than HClO because: TheHatom in HCIO is bound to the Clatom The Cltom in HCIO ismoreeletrogative than that in HCIO The extra oxygen atom"ushesthe Hatom of of the HCIO:moecue Theextraoxygen atom pulls bondng towards itsef weakening the -H bond in HCIO2 None of the above 4.HBr is a stronger acid than HCI because:
15. How many chelate rings are present in each of the following complexes? Assume that all the donor atoms are involved in coordination. (a) Cu(trien)]2+; (b) [Fe(ox)3] 3-; (c) [Ru(bpy)3] 2+; (d) [Co(dien)2] 3+ ; Part 2 1. Ammonia is a base because: When dissolved in water, OH- ions are produced The nitrogen can donate a lone pair to an acid The nitrogen can accept a proton from an acid None of the above All of the above 2. In an acid-base reaction: Water will always act as a base, capturing a proton from the acid Water will always act as an acid, giving up a proton to the base A proton will be transferred from the acid to the base A proton will be transferred from the base to the acid Water is always a product of the reaction 3. HClO2(aq) is a stronger acid than HClO(aq) because: The H atom in HClO2 is bound to the Cl atom The Cl atom in HClO2 is more electronegative than that in HClO The extra oxygen atom "pushes" the H atom off of the HClO2 molecule The extra oxygen atom pulls bonding electrons towards itself, weakening the O-H bond in HClO2 None of the above 4. HBr is a stronger acid than HCl because: 4
The Bratom is more than the the H-Br bond weaker The Cl atom is more electronegative than the Br atom making the H-Cl bond stronger The Bratom is larger Brions are more soluble than Clions None of the above 5.Perchloric acid,HCIO,is a strong acid.Which of the following statements is true? molecules The perchlorate ion.ClO.is a weak base In an aqueous solution of HCIO []K CAll of the above 6.Dimethyl amine,(CH3)2NH,is a weak base.Which of the following is true? Upnaditio ff imethyamineasa will be produced The proo froman acid will the Natom of the base (CH3)NH2"is a strong acid All of the above 7.For the polyprotic acid HaPO dissolved in water:
The Br atom is more electronegative than the Cl atom, making the H-Br bond weaker The Cl atom is more electronegative than the Br atom making the H-Cl bond stronger The Br atom is larger Br- ions are more soluble than Cl- ions None of the above 5. Perchloric acid, HClO4, is a strong acid. Which of the following statements is true? Solutions of HClO4 will contain insignificant quantities of undissociated HClO4 molecules The perchlorate ion, ClO4 - , is a weak base Ka of perchloric acid is large In an aqueous solution of HClO4, [H3O+ ][OH- ] = Kw All of the above 6. Dimethyl amine, (CH3)2NH, is a weak base. Which of the following is true? Upon addition of a strong acid to aa aqueous solution of dimethylamine, a salt will be produced The proton from an acid will be attracted to the lone pair on the N atom of the base (CH3)2NH2 + is a strong acid Aqueous solutions of dimethylamine will contain very little (CH3)2NH2 + All of the above 7. For the polyprotic acid H3PO4 dissolved in water: 5
CKal <Ka<Ka3 The predominant spiP Theidmostlydue tothe hydrolysis of None of the above 8.If NaNOz)is added to an aqueous solution of the weak acid HNO2: The pH rises CThe pH falls The pH is unaffected 9.Assume you have a basic buffer system composed of ammonia and ammonium chloride. The Henderson-Hasselbach equation is pH=pKa-log lacid /base).Here,the acid and base are: CHao'and OH C H:O'and H2O C NHs and NH" C NH'and NH3 C NH'andOH 10.CaF2 is a sparingly soluble salt.HF is a weak acid.If the pH of a solution of CaFzis lowered,the solubility of CaF2 will: CIncrease CDecrease
Ka1 < Ka2 < Ka3 The predominant species in solution is PO4 -3 The predominant species in solution is HPO4 -2 The solution is acidic mostly due to the hydrolysis of H2PO4 - None of the above 8. If NaNO2(s) is added to an aqueous solution of the weak acid HNO2: The pH rises The pH falls The pH is unaffected 9. Assume you have a basic buffer system composed of ammonia and ammonium chloride. The Henderson-Hasselbach equation is pH = pKa - log{[acid]/[base]}. Here, the acid and base are: H3O+ and OHH3O+ and H2O NH3 and NH4 + NH4 + and NH3 NH4 + and OH- 10. CaF2 is a sparingly soluble salt. HF is a weak acid. If the pH of a solution of CaF2 is lowered, the solubility of CaF2 will: Increase Decrease 6
CNot change Answer: Question1. All of these are true Question 2. A proton is transferred from the acid to the base in an acid-base reaction.Water is not necessarily involved. Question 3. The extraatom in HCIO2 creates more electronegativity at that end of the molecule pulling electron density away from the O-H bond and thus weakening it. Question 4. Cl is more electronegative.This makes the H-CI bond more ionic,thus stronger.Thus. HCI is a weaker acid. Question 5. All of these are true!Strong acids have weak conjugate bases. Question 6. All of these are true!Weak bases have strong conjugate acids. Question 7. None of these are true!Kal>Ka2Ka3,as for any polyprotic acid.Most of the acidity comes from the first dissociation
Not change Answer: Question 1. All of these are true! Question 2. A proton is transferred from the acid to the base in an acid-base reaction. Water is not necessarily involved. Question 3. The extra O atom in HClO2 creates more electronegativity at that end of the molecule, pulling electron density away from the O-H bond and thus weakening it. Question 4. Cl is more electronegative. This makes the H-Cl bond more ionic, thus stronger. Thus, HCl is a weaker acid. Question 5. All of these are true! Strong acids have weak conjugate bases. Question 6. All of these are true! Weak bases have strong conjugate acids. Question 7. None of these are true! Ka1>Ka2>Ka3, as for any polyprotic acid. Most of the acidity comes from the first dissociation. 7
Question9. The base is NH3.The acid is its conjugate,NH4+. Part 3 1.The pKa of HNO2 is 3.37.The pH ofa 0.01 mol dmaqueous solution of No is: A.5.37 B.2.69 C.1.69 D.0.69 2.Which statement is incorrect about water and ice? A.Ice consists of hydrogen-bonded molecules arranged in a 3D-structure B.The density of ice is greater than that of liquid water C.Water has a relatively high value of vH(373 K) D.Water is both a Bronsted acid and base 3.The conjugate base of [H2POis: A.[PO] B.[HPO]2 C.H:PO4 D.[H3P2O7 4.Which of the following statements is incorrect about oxalic acid (H2C2O)for which K(1)=5.9x102andK(2)=6.4x10? A.The observation that Ka(1)>K(2)is general for dibasic acids B.Both H2C2O and its conjugate base behave as weak acids C.pKa(I)>pKa(2) D.Oxalic acid forms salts including Na2C2O,MgC2O and KHC2O
Question 9. The base is NH3. The acid is its conjugate, NH4+. Part 3 1. The pKa of HNO2 is 3.37. The pH of a 0.01 mol dm–3 aqueous solution of HNO2 is: A. 5.37 B. 2.69 C. 1.69 D. 0.69 2. Which statement is incorrect about water and ice? A. Ice consists of hydrogen-bonded molecules arranged in a 3D-structure B. The density of ice is greater than that of liquid water C. Water has a relatively high value of ΔvapH(373 K) D. Water is both a Brønsted acid and base 3. The conjugate base of [H2PO4] – is: A. [PO4] 3– B. [HPO4] 2– C. H3PO4 D. [H3P2O7] – 4. Which of the following statements is incorrect about oxalic acid (H2C2O4) for which Ka(1) = 5.9 x 10–2 and Ka(2) = 6.4 x 10–5? A. The observation that Ka(1) > Ka(2) is general for dibasic acids B. Both H2C2O4 and its conjugate base behave as weak acids C. pKa(1) > pKa(2) D. Oxalic acid forms salts including Na2C2O4, MgC2O4 and KHC2O4 8
5.Which statement is incorrect? A.H2SO is dibasic B.H3PO is tribasic C.HaPO2 is tribasic D.HEDTA is tetrabasic 6.[Fe(OH2is prepared in acidic solution because A.[Fe(His a Brensted acid in aqueous solution B[Fe(OH2is stabilized against reduction in acid C.[Fe(H)is not soluble in water at pH 7.0 D[Fe(His a Bronsted base in aqueous solution 8.The Gibbs energy change for KCI(s)KCl(aq)at 298 K is given by: A.△dG°(298K) B.△mG°(298K) C.△atiG(298K)+△aG°(298K) D.-△hcG°(298K)-△，G(298K) 10.Which statement is incorrect about the formation of [Co(NH3)6 from [Co(OH2) A.It is likely that log K>log K2>log K3 B.B6=KK2K3K4KsK6 C.log B6=Elog Kn D.K4 refers to the process:[Co(OH2)(NH3)+NH3 [Co(OH2)(NH3)s]+H2O 11.The conjugate acid of [Ti(OH2)s(OH)is A.[Ti(OH2)6] B.[Ti(OH2)4(OH)2]" C.[Ti(OH2)sO D.[(H2O)Ti(p-OH)2Ti(OH2)4]
5. Which statement is incorrect? A. H2SO4 is dibasic B. H3PO4 is tribasic C. H3PO2 is tribasic D. H4EDTA is tetrabasic 6. [Fe(OH2)6] 3+ is prepared in acidic solution because: A. [Fe(OH2)6] 3+ is a Brønsted acid in aqueous solution B [Fe(OH2)6] 3+ is stabilized against reduction in acid C. [Fe(OH2)6] 3+ is not soluble in water at pH 7.0 D [Fe(OH2)6] 3+ is a Brønsted base in aqueous solution 8. The Gibbs energy change for KCl(s) → KCl(aq) at 298 K is given by: A. Δ hydGo (298 K) B. Δ solGo (298 K) C. Δ latticeGo (298 K) + Δ hydGo (298 K) D. –Δ latticeGo (298 K) – Δ hydGo (298 K) 10. Which statement is incorrect about the formation of [Co(NH3)6] 2+ from [Co(OH2)6] 2+? A. It is likely that log K1 > log K2 > log K3 B. β6 = K1K2K3K4K5K6 C. log β6 = ∑log Kn D. K4 refers to the process:[Co(OH2)2(NH3)4] 2+ + NH3 = [Co(OH2)(NH3)5] 2+ + H2O 11. The conjugate acid of [Ti(OH2)5(OH)]2+ is: A. [Ti(OH2)6] 3+ B. [Ti(OH2)4(OH)2] + C. [Ti(OH2)5O]+ D. [(H2O)4Ti(μ-OH)2Ti(OH2)4] 4+ 9
13.At 298 K,the standard enthalpy change for the process:Na'(g)Na'(aq)is: A△dH(298K) B.△slH(298K) C.-△apH298K) D.△H(298K) 14.The ligand 1,10-phenanthroline(phen)is typically A.bidentate,and an N,N'-donor B.monodentate,and an N-donor C.bidentate,and an.O'-donor D.monodentate,and an O-donor 15.In the complex [K(18-crown-6)+,the number of 5-membered chelate rings that are formed is: A.6 B.4 C.2 D.0 16.When [EDTA]coordinates to a metal ion,M2,to give [M(EDTA)],the number of chelate rings formed is: A.4 B.5 c.6 D.3 17.Within the HSAB principle,a hard acid: A.is not very polarizable B.has a low charge density C.shows a preference for soft bases D.shows a preference for donor atoms of low electronegativity
13. At 298 K, the standard enthalpy change for the process: Na+ (g) → Na+ (aq) is: A. ΔhydHo (298 K) B. ΔsolHo (298 K) C. –ΔvapHo (298 K) D. ΔfHo (298 K) 14. The ligand 1,10-phenanthroline (phen) is typically: A. bidentate, and an N,N'-donor B. monodentate, and an N-donor C. bidentate, and an O,O'-donor D. monodentate, and an O-donor 15. In the complex [K(18-crown-6)]+, the number of 5-membered chelate rings that are formed is: A. 6 B. 4 C. 2 D. 0 16. When [EDTA]4- coordinates to a metal ion, M2+, to give [M(EDTA)]2-, the number of chelate rings formed is: A. 4 B. 5 C. 6 D. 3 17. Within the HSAB principle, a hard acid: A. is not very polarizable B. has a low charge density C. shows a preference for soft bases D. shows a preference for donor atoms of low electronegativity 10