09_Complex_Acid-Base_Titrations-page2

09_Complex_Acid-Base_Titrations-page2 - KA1 / KA2 =...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: KA1 / KA2 = 7.5x10-3 / 6.0x10-8 = 1.25 x 105 KA2 / KA3 = 6.0x10-8 / 4.8x10-13 = 1.25 x 105 This indicates that it is possible to treat each step separately during a titration. Just because you have a material where KA1/KA2 is not greater than 1000 does not mean it can’t be titrated. We’ll now review the calculations involved for the titration of a ‘well behaved’ diprotic acid. It is still possible to determine equilibrium concentrations at any point during a titration. This really is nothing more that doing two separate sets of calculations. However, when KA1/KA2 < 1000, you don’t get a sharp ‘first’ endpoint. You can Titrate to the ‘final endpoint’ Titrate to a form where Kx/KY > 1000. Triprotic acids (or higher) simply amount to repeating the process as many times as necessary. Construct a curve for the titration of 25.00 ml of 0.1000 M sodium carbonate (Na2CO3) with 0.1000 M HCl. KB1 = 2.00 x 10-4 = [ OH- ] [ CO32- ] [HCO3- ] KB2 = 2.51 x 10-8 = [ OH ] [HCO3 ] [ H2CO3 ] KB1 / KB2 = 8.00 x so our base is ‘well behaved’ and we can treat each equilibrium separately. 103 KB1 = 2.00 x 10-4 = [ OH- ] [ CO32- ] [HCO3- ] [ OH- ] = [ CO32- ] [ HCO3- ] = 0.1000M - [ CO32- ] ...
View Full Document

This note was uploaded on 01/07/2012 for the course CHEM 290 taught by Professor Harvey during the Fall '08 term at SUNY Stony Brook.

Ask a homework question - tutors are online