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### Transcript of Chapter 7 Electrochemistry - Shandong Example: The conductivity of a saturated AgCl solution is 1.86

• Chapter 7 Electrochemistry

§7.3 Applications of Conductivity Measurement

• 1. Monitor the purity of water

Silicon wafer

Integrated circuit

Fabrication of VLSI

§7.3 Applications of Conductivity Measurement

• 1. Monitor the purity of water Fabrication of VLSI

§7.3 Applications of Conductivity Measurement

Silicon wafer

• In-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 ⎯ standard cleaning：

SC-1: H2O2/NH3; SC-2: H2O2/HCl.

1. Monitor the purity of water Fabrication of VLSI

water Tap

water

Distilled

water

Deionized

water

Pure

water

/S·m-1 1 10-2 ~1 10-3

• 2. Measure the ionizability and dissociation constant

m

( )c Z F U U

c  + + + −

+ =

c+ =c

m ( )U U F  + −= +

At infinite dilution

m ( )F U U   

+ −= +

m

m

( )

( )

U U F

U U F

  

 + −

  

+ −

+ = =

+

Arrhenius suggested that the degree of

dissociation of an electrolyte can be

calculated using molar conductivity.

§7.3 Applications of Conductivity Measurement

• 22 2 2

m

m m m(1 ) 1 ( )

cc c K

c

 

      = = =

− − −

Ostwald dilution law

Ostwald showed how one can measure the

dissociation constant of an acid.

The equation can be rearranged to

m2

m m m

1 1 1 ( )

a

c K

    

= +

Linearization

2. Measure the ionizability and dissociation constant

§7.3 Applications of Conductivity Measurement

• 3. Determine solubility and solubility products

-Ag Ag Cl Cl H H OH OH c c c c    + + − + + − −= + + +

w Ag Ag Cl Cl Ag Cl ( )c c S     + + − − + −− = + = +

w w

mAg Cl

S    

  + − 

− − = =

+

Example: The conductivity of a saturated

AgCl solution is 1.86  10-4 S·m-1, while

that of water used for preparation the

solution is 6.0  10-6 S·m-1. Given that the

molar conductivity of AgCl is 0.01372

S·mol-1·m2. Calculate the solubility

product for AgCl. What assumption have we made?

§7.3 Applications of Conductivity Measurement

• 4. Determine ion product of water

Water can be taken as a dilute solution

of a strong electrolyte

CH+ = COH- = Kw 1/2

m m,H m,OHc

   + −

  = = +

The specific conductance of highly purified

water is 5.478 10-6 S·m-1. Calculate the

concentration of hydrogen ion in water.

-1 2

m m,H m,OH 0.05481S mol m  + −

  = + =  

6 1

1 2

m

4 3

7 3

5.478 10 S m

0.05481S mol m

0.9995 10 mol m

1 10 mol dm

c 

− −

 −

− −

− −

  = =

 

=  

  

§7.3 Applications of Conductivity Measurement

• 5. Conductometric titration (the way to determine endpoint)

The conductance variation of a solution

during titration can serve as a useful

method to follow the course of the

reaction.

Na+ + OH- + (HCl) = Na+ + Cl- + (H+ + Cl-)

5.19 20.52 5.19 7.91 36.30

Precipitation reactions,

neutralization reactions,

coordination reactions

A

B

C

A’

B’

C’

V / ml

 /

S ·m

-1

endpoint

§7.3 Applications of Conductivity Measurement

• 5. Conductometric titration

§7.3 Applications of Conductivity Measurement

• 6. Study on ionic channel in cell membrane

§7.3 Applications of Conductivity Measurement

• 6. Study on ionic channel in cell membrane

§7.3 Applications of Conductivity Measurement