Modern Chemistry Chapter 15 Acid-Base Titration

1
Modern Chemistry Chapter 15Acid-Base Titration
pH
2
Section 1

• self-ionization of water occurs when two water
  molecules produce a hydronium (H3O) and a
  hydroxide (OH-) ion
• 2 H2O ? H3O OH-
• The ionization constant (Kw) of water is Kw
  H3O OH- 1.0 x 10-14 M

3
Acidic, Basic, Neutral

• IF H3O gt OH- then solution is acidic.
• IF H3O lt OH- then solution is basic.
• IF H3O OH- then solution is neutral.

4
Calculating H3O OH-

• Since the product of the hydronium and hydroxide
  ion concentrations is a constant, we can use the
  following formula to determine these
  concentrations.
• H3O OH- 1.0 x 10-14 M
• Use this formula to answer problems 1-4 on page
  502 of the textbook.

5
The pH Scale

• The pH of a solution is defined as the negative
  of the common logarithm of the hydronium ion
  concentration, H3O.
• pH -log H3O
• The pOH of a solution is defined as the negative
  of the common logarithm of the hydroxide ion
  concentration, OH-.
• pOH -log OH-

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pH pOH

• pH pOH 14 so
• 14 pH pOH and
• 14 pOH pH
• See figure 3 on page on page 503.
• See table 3 on page 504.
• See table 4 on page 504.
• Do problem 1 on page 505.
• Do problems 1-4 on page 506.
• Do problems 1-4 on page 508.

7
Cross-Disciplinary Connection

• Read the Cross-Disciplinary Connection titled
  Liming Streams on page 510.
• Answer both questions at the end of the article.

8
Section 2Determining pH and Titrations

• acid-base indicators are compounds whose colors
  are sensitive to pH
• transition interval is the pH range over which an
  indicator changes color
• a pH meter determines the pH of a solution by
  measuring the voltage between two electrodes
  placed in a solution.

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Titration

• titration is the controlled addition and
  measurement of the amount of a solution of a
  known concentration required to react completely
  with a measured amount of solution of an unknown
  concentration
• equivalence point is the point at which the two
  solutions used in a titration are present in
  chemically equivalent amounts
• endpoint is the point in a titration at which the
  indicator changes color
• standard solution is the solution that contains a
  precisely known concentration of solute

10
Titration

• see figure 10 on pages 518-519 for the steps of a
  titration
• A general equation for the solution of titration
  problems would be
• VaMaeqa VbMbeqb
• Va volume of acid Vb volume of base
• Ma molarity of acid Mb molarity of base
• eqa H in formula of acid eqb OH in formula
  of base

11
Titration

• Do practice problems 1-2 on page 521.
• Do section review problems 1-2 on page 521.
• Do chapter review problems 6, 8, 9, 12, 13, 24,
  25, 26 on pages 523-524.

12
Modern Chemistry Chapter 15Test Review

• 25 multiple choice
• definition of self-ionization
• H3O OH- 1 x 10-14
• definition and formula for calculating pH
  -logH3O
• pH gt7 is a base pH lt7 is an acid pH 7 is
  neutral
• pH range is normally 0 to 14
• calculate pH from H3O
• calculate H3O from pH
• definitions of indicators, transition interval,
  titration, neutralization, endpoint, standard
  solution
• acid-base titration monitors pH
• titration problems using VaMaeqa VbMbeqb