exam3a - Chemistry 122 Exam 3A Fall 2004 MULTIPLE CHOICE...

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MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) Which is the net ionic equation for the neutralization reaction of a strong acid with the weak base ammonia? A) HCl( aq ) + NH 3 ( aq ) Ì NH 4 Cl( aq ) B) H 3 O + ( aq ) + NH 3 ( aq ) Ì NH 4 + ( aq ) + H 2 O( l ) C) H 3 O + ( aq ) + OH - ( aq ) Ì 2 H 2 O( l ) D) HCl( aq ) + NaOH( aq ) Ì H 2 O( l ) + NaCl( aq ) 2) What is the value of the equilibrium constant for the neutralization of acetic acid with sodium hydroxide? The K a for acetic acid is 1.8 ˛ 10 -5 and the reaction of interest is CH 3 CO 2 H( aq ) + NaOH( aq ) Ì H 2 O( l ) + NaCH 3 CO 2 ( aq ). A) 5.6 ˛ 10 -10 B) 1.8 ˛ 10 9 C) 1.8 ˛ 10 -8 D) 1.8 ˛ 10 -19 3) What is the hydronium ion concentration in a solution prepared by mixing 50.00 mL of 0.10 M HCN with 50.00 mL of 0.020 M NaCN? Assume that the volumes of the solutions are additive and that K a = 4.9 ˛ 10 -10 for HCN. A) 7.0 ˛ 10 -6 M B) 2.4 ˛ 10 -9 M C) 4.9 ˛ 10 -10 M D) 9.8 ˛ 10 -11 M 4) What is the pH at the equivalence point of a titration of the weak base OCl - ( aq ) with the strong acid HCl( aq ) if 20.00 mL of NaOCl solution requires 28.30 mL of 0.50 M HCl to reach the equivalence point? K a = 3.0 ˛ 10 -8 for HOCl. A) 0.30 B) 4.03 C) 3.76 D) 3.18 5) What is the pH of the solution that results when 0.005 moles of KOH is added to 0.100 L of a buffer solution that is 0.100 M in H 2 PO 4 - and 0.100 M HPO 4 2- ? K a2 = 6.2 ˛ 10 -8 for phosphoric acid. A) 5.61 B) 6.73 C) 5.21 D) 7.68 6) Which one of the following statements about buffers is true? A) Buffers consist of a strong acid and its conjugate base. B) A buffer does not change pH on addition of a strong acid or strong base. C) All buffers have a pH = 7. D) Buffers resist changes in pH upon addition of small amounts of strong acid or
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This note was uploaded on 11/29/2010 for the course CHEM 122 taught by Professor Abrahamson during the Fall '08 term at North Dakota.

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exam3a - Chemistry 122 Exam 3A Fall 2004 MULTIPLE CHOICE...

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