Title: Chapter 7 Electrochemistry
1Chapter 7 Electrochemistry
7.3 Applications of Conductivity Measurement
- Main contents
- Monitoring the purity of water
- Measurement of ionizability
- Determination of solubility product and ionic
product - Conductometric titration
21. Monitor the purity of water
Group works Calculate the conductivity of
pure water. at 25 oC, Kw 10-14, H OH?
10-7 moldm-3
water Tap water Distilled water Deionized water Pure water
?/Sm-1 1 ?10-2 1 ?10-3 lt1 ?10-4 5.478 ?10-6
Fabrication of VLSI
3In-situ monitoring of the cleaning process
H2O2/H2SO4 ? DW rinse ? dilute HF ? SC-1
cleaning ? DW rinse ? hot DW rinse ? DW rinse ?
SC-2 cleaning ? DW rinse ? dilute HF ? DW rinse.
DW - deionized water, SC-1
H2O2/NH3 SC standard cleaning,
SC-2 H2O2/HCl.
42. Measure the ionizability and dissociation
constant
c ?c
At infinite dilution
Arrhenius suggested that the degree of
dissociation of an electrolyte can be calculated
using molar conductivity.
5Ostwald showed how one can measure the
dissociation constant of an acid.
Ostwald dilution law
The equation can be rearranged to
Linearization
63. Determine solubility and solubility products
Example The conductivity of a saturated AgCl
solution is 1.86 ? 10-4 Sm-1, while that for
water is 6.0 ? 10-6 Sm-1. Molar conductivity of
AgCl is 0.01372 Smol-1m2. Calculate the
solubility product for AgCl.
75. Determine ion product of water
Water can be taken as a dilute solution of a
strong electrolyte
CH COH- Kw1/2
The specific conductance of highly purified water
is 5.478 ?10-6 Sm-1. Calculate the concentration
of hydrogen ion in water.
86. Conductometric titration
The conductance variation of a solution during
titration can serve as a useful method to follow
the course of the reaction.
Ionic mobility of ions
Na OH- (HCl) 5.19 20.52
Na Cl- (H Cl-) 5.19 7.91
36.30
Precipitation reactions, neutralization
reactions, and coordination reactions
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10Homework
Due time Sep. 24