mol of added base 36. Equal moles of which of the following chemicals could be used to make a basic (1 mark)

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1 Consider the following titration curve: Consider the following titration curve: ph ph ph mol of added base Select a suitable indicator for this 1 titration. mol of added base (1 mark) Select A. orange a suitable IV indicator for this titration. mol of added base (1 mark) B. methyl red Select A. C. orange thymolphthalein a suitable IV indicator for this titration. B. D. methyl indigo carmine red A. C. orange thymolphthalein IV B. D. methyl indigo carmine red C. thymolphthalein D. indigo carmine 35. Calculate the volume of. 3 M HNO 3 needed to completely neutralize 5. ml of. 5 M Sr( OH). Calculate the volume of. 3 M HNO 3 needed to completely neutralize 5. ml ( marks) of A M mlsr( OH). ( marks) B. 15. ml A. 1 4 ml C.. 8 ml B. 15. ml D ml C.. 8 ml D ml Equal moles of which of the following chemicals could be used to make a basic buffer solution? (1 mark) 36. Equal moles of which of the following chemicals could be used to make a basic buffer A. HF solution? and NaOH (1 mark) B. HCl and NaCl A. HF and NaOH C. KBr and NaNO B. HCl and NaCl 3 D. NH C. KBr 3 and NH4Cl and NaNO Which D. NHreaction 3 and NH occurs 4Cl when calcium oxide is added to water? (1 mark) OVER 13 A. CaO( s) CaO OVER B. CaO 13 ( s) Ca O C. CaO( s) HO( l) Ca OH D. CaO( s) HO( l) CaOH O

2 63. A chemical indicator in solution consists of A. a weak acid and its conjugate acid. B. a weak acid and its conjugate base. C. a strong acid and its conjugate acid. D. a strong acid and its conjugate base. 64. A chemical indicator has a transition point at a poh = 8.. Calculate its K a value and identify the indicator. A. K a = 1 1 8, phenol red B. K a = 1 1 6, methyl red C. K a = 1 1 8, thymol blue D. K a = 1 1 6, chlorophenol red 65. In acidbase titrations, the solution of known concentration is called a(n) A. basic solution. B. acidic solution. C. standard solution. D. indicating solution. 66. During a titration, 5. ml of H3PO4 is completely neutralized by 4. 6 ml of. M NaOH. Calculate the concentration of the acid. A.. 11M B.. 17 M C.. 34 M D. 1. M 67. Write the net ionic equation for the neutralization of HF with Sr( OH) ( aq ). A. HF OH HO( l) F B. HF HO( l) H3O F C. HF Sr OH SrF H O l D. H F Sr OH SrF HO( l)

3 68. Consider the buffer equilibrium: HNO H O H O NO high concentration aq 3 aq aq ( l) low concentration high concentration What happens when a small amount of HCl is added to the equilibrium system? A. The ph increases slightly. B. The ph decreases slightly. C. The equilibrium shifts to the right. D. The equilibrium does not shift due to the levelling effect. 69. The indicator phenol red will be red in which of the following solutions? A. 1. M HF B. 1. M HBr C. 1. M NH4Cl D. 1. M NaCO3 7. Which of the following chemical indicators has a K a = ? A. methyl orange B. phenolphthalein C. thymolphthalein D. bromcresol green 71. At a certain point in a strong acidstrong base titration, the moles of H are equal to the moles of OH. This is a definition of which of the following? A. the end point B. the titration point C. the transition point D. the equivalence point 7. A 5. ml sample of HSO4 is titrated with ml of. 5 M NaOH. What is the concentration of the HSO4? A.. 78 M B.. 16 M C.. 31 M D.. 6 M

4 73. What is the complete ionic equation for the neutralization of. 1M Sr( OH) ( aq ) with. 1M HSO4? A. H OH $ H O l B. Sr SO4 ( aq ) $ SrSO4 s () C. Sr OH H SO4 $ SrSO4 s HO l D. Sr OH H SO4 $ Sr SO4 HO l 74. Carbon dioxide gas in the atmosphere dissolves in normal rainwater. This causes normal rainwater to A. be slightly basic. B. have a ph slightly less than 7.. C. be unaffected and remain neutral. D. have a ph slightly greater than What is true about the transition point of all indicators described by the following equilibrium: HIn H O & H O In 3 A. ph = K a [ ]= [ ] B. HIn In 7 C. [ H3O ]= 1. 1 M D. moles of H O 3 equals moles of OH 76. A chemical indicator has a K a = What is the ph at the transition point and the identity of the indicator? ph Indicator A. 54. methyl red B. 54. bromcresol green C. 86. phenolphthalein D. 86. thymol blue

5 77.. A. ml sample of HCl is titrated with 5. ml of. M Sr OH What is the concentration of the acid? A.. 13M B.. M C.. 5 M D.. 5 M 78. Which of the following is the net ionic equation for the neutralization of HNO 3 with Sr( OH) ( aq )? A. H OH ' H O l aq 3 aq 3 ( s) B. Sr NO Sr NO ' C. HNO Sr OH Sr NO H O ' l 3 3 D. H NO3 Sr OH ' Sr NO3 HO l 79. When a strong acid is titrated with a strong base, what will the ph value be at the equivalence point? A.. B C. 7. D Which of the following acids could not be present in a buffer solution? A. HF B. HNO C. HSO3 D. HClO 4 Written 1. A titration was performed by adding. 115 M NaOH to a 5. ml sample of HSO 4. Calculate the HSO4 [ ] from the following data. (3 Trial #1 Trial # Trial #3 Initial volume of NaOH ( ml) Final volume of NaOH ( ml)

6 . A titration was performed by adding. 175 M HCO 4 to a 5. ml sample of NaOH. The following data was collected: Trial #1 Trial # Trial #3 Final volume of HCO4( ml) Initial volume of HCO4( ml) a) Calculate the [ NaOH]. (3 marks) b) Explain why the ph at the equivalence point is greater than A 5. ml sample of HCl with a ph of. is completely neutralized with. M NaOH. a) What volume of NaOH is required to reach the stoichiometric point? b) Write the net ionic equation for the above neutralization reaction. c) If the HCl were titrated with a. M NH3 instead of. M NaOH, how would the volume of base required to reach the equivalence point compare with the volume calculated in part a)? Explain your answer. 4. a) In the space below, sketch the titration curve for the reaction when. 1 M HCl is added to 1. ml of. 1 M NaOH. ph Volume of added HCl (ml) b) Describe two changes in the titration curve that would result from using. 1 M CH3COOH in place of the HCl.

7 5. 6. [ ] 5 3 Calculate the OH in. M NH aq. An indicator is often used during acidbase titrations. a) Define the term transition point for an indicator. b) Calculate the K a value for methyl red. c) A mixture of indicators is made by combining equal amounts of methyl orange and bromthymol blue. Complete the following table, showing the colour of each indicator and the mixture at ph of 5 and ph of 9. methyl orange bromthymol blue mixture ph=5 ph=9 7. A. 1M unknown acid is titrated with. 1 M NaOH and the following titration curve results: ph Volume of.1 M NaOH added a) Choose a suitable indicator (other than phenolphthalein) and give a reason for your choice. b) Is the unknown acid weak or strong? Explain.

8 MultipleChoice Answers 1 B 6 C 11 A 16 B 1 C 6 A 31 D 36 B 41 A 46 A D 7 C 1 D 17 C D 7 A 3 A 37 D 4 D 47 A 3 C 8 C 13 B 18 B 3 D 8 C 33 A 38 A 43 D 48 D 4 D 9 C 14 C 19 B 4 A 9 B 34 C 39 D 44 D 49 C 5 D 1 D 15 A B 5 A 3 B 35 B 4 B 45 B 5 B 51 C 56 B 61 D 66 A 71 D 76 A D 57 B 6 C 67 A 7 B 77 D D 58 B 63 B 68 B 73 C 78 A D 59 C 64 D 69 D 74 B 79 C B 6 D 65 C 7 D 75 B 8 D Solutions to Written 1. NaOH H SO Na SO H O 4 4 vol of NaOH = 11. ml mol NaOH. 11 L. 115mol L mol = = = mol H SO = mol NaOH mol mol [ HSO4]=. 5 L =. 53 M a) H C O NaOH Na C O H O 4 4 vol H C O 4 = 16. ml mol H C O =. 16 L (. 175 mol L) =. 8 1 mol 4 3 mol NaOH = mol H C O = mol mol [ NaOH]= =. 4 M. 5 L 3 b) The CO 4 ion resulting from the dissociation of Na C O hydrolyzes to form a basic solution. 4

9 3. a) H3O OH HO [ HCl]= 1. 1 M mol HCl. 5L 1. 1 mol L = =. 5 1 mol HCl = mol NaOH 3 mol Volume of NaOH = mol. M = L b) c) The volume of base required would not change, because the strong acid results in the reaction going to completion in a 1:1 ratio. 4. a) In the space below, sketch the titration curve for the reaction when. 1 M HCl is added to 1. ml of. 1 M NaOH. ph mark for general shape 1 mark for showing curve drop 1 mark for location of equivalence point Volume of added HCl (ml) b) Any two of the following for 1 mark each. The equivalence point is > 7. The vertical part of the curve is shorter. Buffer region.

10 5. K b Kw 1. 1 = = K a 14 1 = NH H O NH OH [] I. 5 [ C] x x x [ E]. 5 x x x K b [ NH ][ OH ] 4 = = NH [ 3] Use assumption that. 5 x. 5 or use the quadratic formula. x = [ OH ]= 3. 1 ( x)( x). 5 x = 3 M a) The point where the indicator is halfway through the colour change. OR [ HInd]= [ Ind ] b) Average ph = K a = 1 1 = = 54. c) methyl orange bromthymol blue mixture ph=5 ph=9 yellow yellow yellow yellow blue green 7. a) Suitable Indicator: Thymol blue Reason: The transition point is close to the equivalence point.

11 b) Unknown Acid: Weak For example any one of the following for 1 mark each: Explanation: the shape of the curve is characteristic of a weak acid being titrated with a strong base the initial ph is greater than 1. the ph at the equivalence point is greater than 7.