Exam 2 - Version Exam 2 holcombe 2. neutral 3. acidic...

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Version – Exam 2 – holcombe – 1 This print-out should have 32 questions. Multiple-choice questions may continue on the next column or page – fnd all choices beFore answering. 001 10.0 points Solutions A and B have equal volumes. The concentration oF hydronium ion in solution B is 100 times smaller than in solution A. IF the pH oF solution A is 7, what would be the pH oF solution B? 1. 6 2. 3 3. 5 4. 9 correct 5. 8 Explanation: pH A = 7 [H 3 O + ] B = [H 3 O + ] A 100 = 10 7 10 2 = 10 9 M pH = log(10 9 ) = 9 002 10.0 points Which oF the Following salts produces a neu- tral solution when it is dissolved in water? 1. NaClO 2. KCH 3 CO 2 3. NaBr correct 4. Li± 5. KCN Explanation: 003 10.0 points Adding NH 4 BrO to pure water would result in what kind oF solution? K a For HBrO is 2 . 5 × 10 9 and K b For NH 3 is 1 . 8 × 10 5 . 1. basic correct 2. neutral 3. acidic Explanation: 004 10.0 points A solution with a higher pH is more acidic. 1. The answer cannot be determined with- out additional inFormation. 2. True 3. ±alse correct Explanation: pH = log [H 3 O + ], so as [H 3 O] increases, pH decreases. 005 10.0 points An aqueous solution is known to have a pH oF 5.30 at 25 C. What is the concentration oF OH in the solution? 1. 5 . 01 × 10 8 M 2. 2 . 00 × 10 9 M correct 3. 1.89 M 4. 8.70 M 5. 1 . 00 × 10 2 M 6. 5 . 01 × 10 6 M Explanation: pH = 5.30 pOH = 14 pH = 8 . 7 [OH ] = 10 pOH = 10 8 . 7 M = 1 . 99526 × 10 9 M 006 10.0 points What is the pOH in a solution made by
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– Exam 2 – holcombe – 2 dissolving 0.100 mole of sodium acetate (NaCH 3 COO) in enough water to make one liter of solution? K a for CH 3 COOH is 1 . 80 × 10 5 . 1. 5.74 2. 5 . 56 × 10 10 3. 8.87 4. 1 . 34 × 10 9 5. 1 . 34 × 10 3 6. 5.13 correct 7. 7 . 46 × 10 6 8. 2.87 9. 9.25 10. 1 . 80 × 10 6 Explanation: 007 10.0 points What would be the pH of a 0 . 4 M Na 2 CO 3 solution? Carbonic acid has K a 1 = 2 . 5 × 10 4 , K a 2 = 5 . 6 × 10 11 . 1. 8.60 2. 7.00 3. 11.93 correct 4. 2.07 5. 5.40 Explanation: Na + is a spectator, and CO 3 2 is a weak base. K b 2 = K w K a 2 = 10 14 5 . 6 × 10 11 = 1 . 8 × 10 4 [OH ] = ( K b C b ) 1 / 2 = ( (1 . 8 × 10 4 )0 . 4 ) 1 / 2 = 8 . 45 × 10 3 M pH = 11 . 93 008 10.0 points What would be the pH of a 10 9 M solution of HCl? 1. 6.921 2. 6.954 3. 6.876 4. 6.998 correct Explanation: For a dilute strong acid, [H + ] 2 Ca[H + ] K w = 0 [H + ] = x = p b ± b 2 4ac 2a P pH = 6.998 009 10.0 points The equilibrium constant for N 2 O 4 2 NO 2 has the numerical value of 0.0466. If the initial concentrations are [N 2 O 4 ] = 1.0 M, [NO 2 ] = 0.0 M, what are the ±nal concentrations of [N 2 O 4 ] and [NO 2 ], respectively? 1.
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This note was uploaded on 11/12/2010 for the course CH 302 taught by Professor Holcombe during the Fall '07 term at University of Texas at Austin.

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Exam 2 - Version Exam 2 holcombe 2. neutral 3. acidic...

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