1. Buffers In general, what is a buffer?????
Acids, Bases and Salts
Buffers
In general, what is a buffer????? 
Definitions of buffer

2. Buffers H2O(l) + CO2 (g) H2CO3 (aq)
Acids, Bases and Salts
Buffers
H2O(l) CO2 (g) H2CO3 (aq)
NPR - Increased CO2 levels damage 04/17/13

3. Acids, Bases and Salts Buffers
A buffer is a mixture that is able to release or absorb H+ keeping the pH of a solution constant.
Most common buffers are mixtures of weak acids and their conjugate bases.
weak acid conjugate base
  HC2H3O2 (aq) C2H3O2-(aq)   
H3O+(aq) C2H3O2-(aq)  H2O(l) + C2H3O2(aq)
   OH-(aq) + HC2H3O2 (aq)  H2O(l) + C2H3O2-(aq)
Narrated animation

4. Acids, Bases and Salts blood In the human body an important buffer is
carbonic acid bicarbonate
H2CO3(aq) HCO3-(aq)
weak acid conjugate base   
H3O+(aq) + HCO3-(aq)  H2O(l) + H2CO3(aq)
  OH-(aq) + H2CO3(aq)  H2O(l) + HCO3-(aq)
 Buffer Capacity - the amount of acid or base that a
buffer can neutralize.
blood

5. Acids, Bases and Salts
Acid - Base Titration – controlled neutralization reaction between a solution of known concentration and a solution of unknown concentration.
Used to determine the concentration of a solution.
Solution of known concentration = Standard Solution

6. Acids, Bases and Salts Using an indicator to determine the end point,
measure the amount of standard solution needed to
neutralize the solution with the unknown concentration.
Solution of unknown Concentration
Standard Solution
acidic
basic

7. Acids, Bases and Salts Equivalence Point - point at which enough
standard solution is added for all of the
acid to be neutralized by the base.
At equivalence point -> # moles acid = # moles base
  strong acid + strong base = equivalence point at a neutral pH
strong acid + weak base = equivalence point at pH <7 acidic
weak acid + strong base = equivalence point at pH >7 basic
Titration Simulation
Neutralization
/Titration Animation
See graph(s) in notes and plot data points for titration curves.

8. Acids, Bases and Salts Table T L L moles * L = moles * L
(molarity acid) * (volume acid) = (molarity base) * (volume of base)
  moles * L = moles * L
L L
(MA) (VA) = (MB) (VB)
Table T p12

9. Acids, Bases and Salts (MA) (VA) = (MB) (VB) 0.0744 Mol/L or .0744 M
A 43.0 ml volume of NaOH was titrated with 32.0 ml of 0.100M HCl.
What is the molarity of the NaOH?
Mol/L or M

10. Acids, Bases and Salts (MA) (VA) = (MB) (VB) 0.0744 Mol/L or .0744 M
A 43.0 ml volume of NaOH was titrated with 32.0 ml of 0.100M HCl.
What is the molarity of the NaOH?
Mol/L or M

11. Acids, Bases and Salts (MA) (VA) = (MB) (VB) 0.120 Mol/L or 0.120 M
A volume of 25.0 ml of HCl is neutralized by 40.0 ml of M NaOH.
What is the molarity of the HCl solution?
0.120 Mol/L or M

12. Acids, Bases and Salts (MA) (VA) = (MB) (VB) 0.12 Mol/L or 0.12 M
A volume of 25.0 ml of HCl is neutralized by 40.0 ml of M NaOH.
What is the molarity of the HCl solution?
0.12 Mol/L or M