III. Titration (p. 493 - 503)

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III. Titration(p. 493 - 503)

• Ch. 16 Determining pH and Titrations

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Neutralization

• Chemical reaction between an acid and a base.
• Products are a salt (ionic compound) and water.

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• ACID BASE ? SALT WATER

HCl NaOH ? NaCl H2O
strong
strong
neutral
HC2H3O2 NaOH ? NaC2H3O2 H2O
weak
strong
basic

• Salts can be neutral, acidic, or basic.

• Neutralization does not mean pH 7.

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Indicators and pH Meters

• Approximate pH values can be estimated using
  acid-base indicators.
• indicators are compounds whose colors are
  sensitive to pH.
• Change color in acids and bases.
• See pg. 493

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• Transition Interval the pH range over which
  an indicator changes color.
• Pg. 495 gives transition intervals
• pH meter determines the pH of a solution more
  exact measuring voltage.
• Voltage changes when hydronium ion concentration
  changes.

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Titration

• Titration
• Analytical method in which a standard solution is
  used to determine the concentration of an unknown
  solution.

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Equivalence Poont

• Equivalence point (endpoint)
• Point at which equal amounts of H3O and OH- have
  been added.
• Determined by
• indicator color change

• dramatic change in pH

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Molarity and Titration
moles H3O moles OH- M?V? n M?V? n
M Molarity V volume n of H ions in the
acid or OH- ions in the base
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• 42.5 mL of 1.3M KOH are required to neutralize
  50.0 mL of H2SO4. Find the molarity of H2SO4.

H3O M ? V 50.0 mL n 2
OH- M 1.3M V 42.5 mL n 1
MV MV M(50.0mL)(2) (1.3M)(42.5mL)(1) M
0.55M H2SO4
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4 Step Method

• Start with the balanced equation for the
  neutralization reaction.
• Determine the moles of acid (or base) from the
  known solution used during the titration.
• Determine the moles of solute of the unknown
  solution used during the titration.
• Determine the molarity of the unknown solution.
• Good Luck!!