CHM 131 Lecture Notes - Lecture 10: Conjugate Acid, Init, Acid Dissociation Constant

• School: University of Rochester
• Department: Chemistry
• Course: CHM 131
• Professor: Benjamin Hafensteiner

Document Summary

Acetic acid and sodium acetate 0. 1 m. Initial species are hac, na+ , ac- and h2o. In pure weak acid [ac- ] init = 0. The ice man returneth: determine final concs in terms of initial concs. Common-ion effect le chatelier in action. Without added acetate ion the ph of 0. 10 m acetic acid is 2. 89. Addition of ac- causes [h3o+ ] to decrease. Consequence of le chatelier: increasing [product] equilibrium goes to reactants. Compare effect of adding ohto solution of given ph. Almost all the added h+ is converted into hac. Able to predict percent dissociation of an acid from the difference between ph and pka. Calculate relative quantities of acid and conjugate base required to achieve a given ph. Ph= pka + log [ (base)/(acid) ] The glass half-neutered: instead of using a source of weak acid and a conjugate base, take a weak acid and neutralize with strong base to make the conjugate base.