Titrations and titration curves
Announcements
Wednesday, April 14, 2010
Known concentration
MasteringChemistry due dates:
Ch 16: Tuesday Apr 20, 11:59pm
Ch 17: Tuesday Apr 27, 11:59pm
Ch 18: Friday May 7, 11:59pm
Unknown concentration
Titration curves lab report due next Monday.
The report must contain (either as calculations in a
spreadsheet cell or typed out with equation editor in the
result section):
Concentration calculations for each monoprotic acid
Ka found two ways for the weak monoprotic acid (using
initial conc/pH and using halfway point);
% error for each.
Ka1 and Ka2 for the diprotic acid (using two midpoints)
Calculated pH at the equivalence point for the weak
acid, using the more accurate Ka value. Compare this
with your experimental pH at the equivalence point
(% error).
Titration curve:
graph of pH vs volume
of solution added
Strong acid titrated with strong base
pH
Quiz 3 Wednesday Apr 21 on end of Ch 15 and Ch 16.
Vol NaOH added (mL)
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Strong acid titrated with strong base
Weak acid titrated with strong base
50.0 mL HCl of unknown concentration is titrated with
0.150 M NaOH. The titration curve's only inflection point
occurs at 40.0 mL of added base. What was the initial HCl
concentration?
pH
What was the initial pH of the HCl solution?
Vol NaOH added (mL)
HA + OH− →
What is the pH after 60.0 mL NaOH is added?
Buffer region:
At the midpoint (half-equivalence pt):
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Weak acid titrated with strong base
Weak acid titrated with strong base
40.0 mL of 0.0788 M HA are titrated with 0.100 M NaOH.
What is the volume of NaOH added at the equivalence
point?
What is the pH after 10.0 mL 0.100 M NaOH is added to
40.0 mL of 0.0788 M HA (the titration on the last page)?
If the pH = 4.88 at the midpoint, what is Ka and what is
the pH at the endpoint?
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Weak acid titrated with strong base
Weak acid titrated with strong base
75.0 mL of a weak acid are titrated by 0.125 M NaOH.
The endpoint occurs at 62.1 mL of added base, and the
pH at the midpoint is 3.12.
What is the initial acid concentration?
What is the Ka?
What is the pH initially and at the equivalence
point?
75.0 mL of a weak acid are titrated by 0.125 M NaOH.
The endpoint occurs at 62.1 mL of added base, and the
pH at the midpoint is 3.12.
What is the initial acid concentration?
What is the Ka?
What is the pH initially and at the equivalence
point?
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Weak base and polyprotic acid titrations
Weak base titr by strong acid
pH
Vol HCl added (mL)
Polyprotic acid titr by strong base
pH
Vol NaOH added (mL)
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