Transcript Ch. 16-2 Notes

Ch. 16 – Determining pH and
Titrations
III. Titration
(p. 493 - 503)
Neutralization
 Chemical
reaction between an acid and
a base.
 Products are a salt (ionic compound)
and water.
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.
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
 “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.
Titration
 Titration
standard solution
• Analytical method
in which a standard
solution is used to
determine the
concentration of an
unknown solution.
unknown solution
Equivalence Poont
 Equivalence
point (endpoint)
• Point at which equal
amounts of H3O+ and OHhave been added.
• Determined by…
• indicator color change
• dramatic change in pH
Molarity and Titration
+
O
moles H3 = moles
MVn = MVn
M: Molarity
V: volume
n: # of H+ ions in the acid
or OH- ions in the base
OH
 42.5
mL of 1.3M KOH are required to
neutralize 50.0 mL of H2SO4. Find the
molarity of H2SO4.
H3O+
OH-
M=?
M = 1.3M
V = 50.0 mL
n=2
V = 42.5 mL
n=1
MV# = MV#
M(50.0mL)(2)
=(1.3M)(42.5mL)(1)
M = 0.55M H2SO4
4 Step Method
Start with the balanced equation for the
neutralization reaction.
2. Determine the moles of acid (or base) from
the known solution used during the titration.
3. Determine the moles of solute of the
unknown solution used during the titration.
4. Determine the molarity of the unknown
solution.
Good Luck!!
1.