Download presentation
Presentation is loading. Please wait.
1
Lecture 17 10/12/05
2
pH of diprotic acids Leucine H 2 L + ⇄ HL + H + pK a1 = 2.329 HL ⇄ L - + H + pK a2 = 9.747
3
Diprotic acids/bases When adding as H 2 L + or L - first dissociation dominates To solve pH - treat like monoprotic acid or monoprotic base To solve for concentration of all species [L - ] = K a2 (when you added H 2 L - ) [H 2 L + ] = K b2 (when you added L - )
![Diprotic acids/bases When adding as H 2 L + or L - first dissociation dominates To solve pH - treat like monoprotic acid or monoprotic base To solve for concentration of all species [L - ] = K a2 (when you added H 2 L - ) [H 2 L + ] = K b2 (when you added L - )](http://images.slideplayer.com./17/5320162/slides/slide_3.jpg "Diprotic acids/bases When adding as H 2 L + or L - first dissociation dominates To solve pH - treat like monoprotic acid or monoprotic base To solve for concentration of all species [L - ] = K a2 (when you added H 2 L - ) [H 2 L + ] = K b2 (when you added L - )")
4
When adding as HL (add 0.05 M) Use systematic equilibrium Equations Charge balance Mass balance K b expression K a expression K w Substitute to get equation in terms of H + and HL For Mass Balance a ssume: [HL] >> [H 2 L + ] and [HL] >> [L - ] So [HL] 0.05 M Solve for H +
![When adding as HL (add 0.05 M) Use systematic equilibrium Equations Charge balance Mass balance K b expression K a expression K w Substitute to get equation in terms of H + and HL For Mass Balance a ssume: [HL] >> [H 2 L + ] and [HL] >> [L - ] So [HL] 0.05 M Solve for H +](http://images.slideplayer.com./17/5320162/slides/slide_4.jpg "When adding as HL (add 0.05 M) Use systematic equilibrium Equations Charge balance Mass balance K b expression K a expression K w Substitute to get equation in terms of H + and HL For Mass Balance a ssume: [HL] >> [H 2 L + ] and [HL] >> [L - ] So [HL] 0.05 M Solve for H +")
Similar presentations
![Lecture 15 10/05/05 Research Club. What is the charge and mass balance for 0.l5 M phosphoric acid Charge balance: [H + ] = [H 2 PO 4 - ] + 2[HPO 4 -2.](/16/4970005/big_thumb.jpg "Lecture 15 10/05/05 Research Club. What is the charge and mass balance for 0.l5 M phosphoric acid Charge balance: [H + ] = [H 2 PO 4 - ] + 2[HPO 4 -2.>")
