Quiz 6-solutions - Version 050 – Quiz 6 – fakhreddine...

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Unformatted text preview: Version 050 – Quiz 6 – fakhreddine – (51650) 1 This print-out should have 5 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. 001 2.0 points A solution is prepared by mixing 250 mL of 1.00 M CH 3 COOH with 500 mL of 1.00 M NaCH 3 COO. What is the pH of this solution? ( K a for CH 3 COOH = 1 . 8 × 10- 5 ) 1. 4.58 2. 4.44 3. 5.36 4. 4.74 5. 5.05 correct Explanation: V CH 3 COOH = 250 mL [CH 3 COOH] = 1.00 M V NaCH 3 COO = 500 mL [NaCH 3 COO] = 1.00 M [CH 3 COOH] = 250 mmol 750 mL [CH 3 COO- ] = 500 mmol 750 mL pH = p K a + log [CH 3 COO- ] [CH 3 COOH] =- log(1 . 8 × 10- 5 ) + log parenleftbigg 500 250 parenrightbigg = 5 . 04576 002 2.0 points How many grams of NaF (of MW 42.0) would have to be added to 2.00 L of 0.100 M HF to yield a solution with a pH = 4.00? 1. 6.9 g 2. 300 g 3. 0.84 g 4. 60 g correct 5. 36 g Explanation: MW NaF = 42 g V = 2 L [HF] = 0.100 M pH = 4.00 K a = 7 . 2 × 10- 4 pH = p K a + log parenleftbigg...
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This note was uploaded on 07/25/2011 for the course CH 302 taught by Professor Holcombe during the Spring '07 term at University of Texas at Austin.

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Quiz 6-solutions - Version 050 – Quiz 6 – fakhreddine...

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