Lect+23+08

# Lect+23+08 - Lecture 23 Goals Examples for calculating...

• Notes
• nmgarof
• 17

This preview shows pages 1–6. Sign up to view the full content.

Lecture 23 Goals Examples for calculating concentrations and pH of weak acid solutions You will have a plain language understanding of buffers and the species that control buffering. Examples for calculating concentrations and pH of buffers and stressed buffer solutions You will have a conceptual understanding of Acid Base Titration curves and be able to figure out the primary species during titration Calculating the response of pH to titration You will have a plain language understanding of polyprotic acids and their neutralization

This preview has intentionally blurred sections. Sign up to view the full version.

Hydrolysis 4 + 3
Weak Base Hydrolysis Prob. 10.38 The pH = 11.5 at 298 K of an aqueous solution of Na(CN) WHAT IS THE [CN - ] CONCENTRATION? Is HCN a weak Acid? CN - (aq) + H 2 O(l) HCN(aq) + OH - (aq) K a = 6.17 x 10 -10 and K a K b =10 -14 so K b = 1.6 x 10 -5 K b = [OH - ][HCN]/[CN - ] But [CN - ]= [OH - ] because weak base pOH = 2.50 since pH + pOH =14 and pH = 11.5 So [OH - ] = 10 -2.5 = 3.2 x 10 -3 = [HCN] [CN - ] = ([OH - ][HCN]/ K b )= 0.62M

This preview has intentionally blurred sections. Sign up to view the full version.

Buffers A buffer is a solution which maintains a relatively constant pH despite small additions of acid or base. HA(aq) + H 2 O(l) H 3 O + (aq) + A - (aq) If we add both HA and A - to the solution then there is chemical resistance to pH change when we add either acid or base. The equilibrium damps the effect of adding acid or base [ H 3 O + ]= K a ([HA]/[A - ]) and if both HA and A - are large then the [ H 3 O + ] is buffered Many physiological systems are buffered
Calculations with buffers Calculations are similar to the equilibrium calculations in chapter 14 where both

This preview has intentionally blurred sections. Sign up to view the full version.

This is the end of the preview. Sign up to access the rest of the document.
• Spring '08
• SHARP
• pH, buffer solution, Diprotic Acid

{[ snackBarMessage ]}

### What students are saying

• As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

Kiran Temple University Fox School of Business ‘17, Course Hero Intern

• I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

Dana University of Pennsylvania ‘17, Course Hero Intern

• The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

Jill Tulane University ‘16, Course Hero Intern