Titration Notes

Titration Notes - TITRATION WEAK BASE STRONG ACID 29.0 mL...

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TITRATION: WEAK BASE + STRONG ACID 29.0 mL sample of 0.237 M trimethylamine , (CH 3 ) 3 N , is titrated with 0.350 M perchloric acid . After adding 31.2 mL of perchloric acid , the pH is 1.17 Use the Tables link on the toolbar for any equilibrium constants that are required. Feedback: Please note that while the results of the intermediate calculations below are displayed rounded to 3 significant digits, the actual calculations are done internally without rounding. The reaction that occurs is: (CH 3 ) 3 N (aq) + HClO 4 (aq) [(CH 3 ) 3 NH]ClO 4 (aq) The net ionic equation is: (CH 3 ) 3 N (aq) + H 3 O + (aq) (CH 3 ) 3 NH + (aq) + H 2 O (l) mol (CH 3 ) 3 N = 0.237 M 2.90E-2 L = 6.87E-3 mol mol H 3 O + = 0.350 M 3.12E-2 L = 1.09E-2 mol There is excess acid, so all of the (CH 3 ) 3 N reacts. The (CH 3 ) 3 NH + ion is a much weaker acid than HClO 4 , and the pH is controlled by the excess HClO 4 . (CH 3 ) 3 N + H 3 O + (CH 3 ) 3 NH + + H 2 O Initial (mol) 6.87E-3 1.09E-2 0 Change (mol) - 6.87E-3 - 6.87E-3 + 6.87E-3 After rxn (mol) 0 4.05E-3 6.87E-3 Volume total = 2.90E-2 + 3.12E-2 = 6.02E-2 L Molarity of H 3 O + = 4.05E-3 mol = 6.72E-2 M 6.02E-2 L pH = -log( 6.72E-2 ) = 1.17 28.6 mL sample of 0.256 M ammonia , NH 3 , is titrated with
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This note was uploaded on 09/22/2010 for the course CHEM 3 taught by Professor Pedersen during the Fall '08 term at Berkeley.

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Titration Notes - TITRATION WEAK BASE STRONG ACID 29.0 mL...

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