chapter 8 9 n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Chapter 8 & 9 PowerPoint Presentation
Download Presentation
Chapter 8 & 9

Loading in 2 Seconds...

play fullscreen
1 / 29

Chapter 8 & 9 - PowerPoint PPT Presentation


  • 92 Views
  • Uploaded on

Chapter 8 & 9. Acids, Bases & Buffers. Chapter 8 Introducing Acids & Bases. Water pH (Acid rain) in the USA in 2001. Conjugate acids & bases. Relation between [H + ], [OH - ], and pH?. 8-3 Strengths of acids & bases. Strong Acids and Bases

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Chapter 8 & 9' - tomasso


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
chapter 8 9

Chapter 8 & 9

Acids, Bases & Buffers

chapter 8 introducing acids bases
Chapter 8 Introducing Acids & Bases
  • Water pH (Acid rain) in the USA in 2001
8 3 strengths of acids bases
8-3 Strengths of acids & bases

Strong Acids and Bases

  • Common strong acids and bases are listed in Table 8-1.
  • A strong acid or strong base is completely dissociated in aqueous solution.

(8-4)

(8-5)

P.175

8 3 strengths of acids bases1
8-3 Strengths of acids & bases

Carboxylic Acids are Weak Acids and Amines are Weak Bases

  • Ask yourself at p.178
slide8

Metal Ions with Charge ≧2 Are Weak Acids

A proton can dissociate from M(H2O)wn+ to reduce the positive charge on the metal complex.

Relation Between Ka and Kb

P.177

8 4 ph of strong acids bases
8-4 pH of strong Acids & Bases
  • Example at p.180
  • The pH of 4.2 x 10-3 M HClO4 ?
  • The pH of 4.2 x 10-3 M KOH?
  • Can we dissolve base in water and obtain an acidic pH (<7)?
8 5 tools for dealing with weak acids and bases
8-5 Tools for Dealing with Weak Acids and Bases
  • pK the negative logarithm of an equilibrium constant

Weak Is Conjugate to Weak

  • The conjugate base of a weak acid is a weak base. The conjugate acid of a weak base is a weak acid.

P.181

slide11

Using Appendix B

  • Acid dissociation constants appear in Appendix B. Each compound is shown in its fully protonated form.
  • Pyridoxal phosphate is given in its fully protonated form as follows:

P.182

slide14

Fraction of Dissociation

  • Figure 8-4 compares the fraction of dissociation of two weak acids as a function of formal concentration.
  • acid increase as it is diluted.

P.184

chapter 9 buffers
Chapter 9 Buffers

Buffered solution resists changes in pH when small amounts of acids or base are added or when dilution occurs.

  • pH dependence of the rate of a particular enzyme-catalyzed reaction.
  • The rate near pH 8 is twice as the rate at pH 7 or 9
9 3 a buffer in action
9-3 A Buffer in Action
  • Example: find the pH of a buffer solution at p. 198
  • Effect of adding acid to a buffer
9 4 preparing buffers
9-4 Preparing Buffers
  • Example at p. 202
  • In the real life p. 203
slide20

Preparing a Buffer in Real Life

  • Suppose you wish to prepare 1.00 L of buffer containing 0.100 M tris at pH 7.60. When we say 0.100 M tris, we mean that the total concentration of tris plus tris H+ will be 0.100M. 

Procedure:

1. Weigh out 0.100 mol tris hydrochloride and dissolve it in a beaker containing about 800 mL water and a stirring bar. 

2. Place a pH electrode in the solution and monitor the pH.

3. Add NaOH solution until the pH is exactly 7.60. The electrode does not respond instantly.

4. Transfer the solution to a volumetric flask and wash the beaker and stirring bar a few times. Add the washings to the volumetric flask. 

5. Dilute to the mark and mix.

P.202

9 5 buffer capacity 1
9.5 Buffer capacity -1

Buffer capacity measures how well a solution resists changes in pH when acid or base is added.

The greater the buffer capacity, the less the pH changes. 

The amount of H+ or OH-

that buffered solution can

absorb without a significant

change in pH

9 5 buffer capacity 2
9.5 Buffer capacity -2
  • 2) Magnitudes of [HA] and [A-]
  •  the capacity of a buffered soln.
    • Ex : soln A : 5.00 M HOAc + 5.00 M NaOAc
    • soln B : 0.05 M HOAc + 0.05 M NaOAc
    • pH change when 0.01 mol of HCl(g) is added
9 5 buffer capacity 3
9.5 Buffer capacity -3

3) [A-] / [HA] ratio  the pH of a buffered soln.

9 6 how indicators work 1
9.6 How indicators work -1

1) Usually a weak organic acid or base that has distinctly different colors in its nonionized & ionized forms.

HIn(aq) H+(aq) + In-(aq)pKHIn

nonionized ionized

form form

9 6 how indicators work 3
9.6 How indicators work -3

2) The useful pH range for indicator is

pKHIn ± 1

 (Fig 10.3)

encompass the pH at equivalence point

(titration curve)

  • Not all indicators change color at the same pH. (Table 9.3)