Transcript Structure_Property Relathionship of PU

Oleh:
Dr. M. Masykuri, M.Si.
® [email protected]
Program Studi P. Kimia FKIP UNS
Jl. Ir. Sutami 36A Solo
HP. 08121500634
Email: [email protected]
Copyrigh by [email protected]
Solo, May 2009
•
Metode analisis kimia berdasarkan
pada daya hantar listrik suatu larutan
analat
Hukum ohm menyatakan:
I = current (ampere)
E = electromotive force (volts)
R = resistance (ohms)
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The resistance of a sample of homogeneous material,
1 = length (m)
A = cross-section area (m2)
 = characteristic property of the material
termed the resistivity (dalam  m)
(formerly called specific resistance)
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The molar conductivity (, lambda) of an electrolyte is
defined as the conductivity due to one mole and is given by:
C = concentration of the solution in mol L-1,
V = the dilution in L (i.e. the number of litres containing one mole).
K has the dimensions  -1 cm-1,
the units of  are  -1 cm2 mol-1, or in SI units,  -1 m2 mol-1.
The Conductance (G) is defined as :
Luas permukaan
elektroda
1
A
G k
R
l
Daya hantar
listrik (ohm-1)
Jarak antar elektroda
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Tahanan listrik (ohm)
Daya hantar ekivalen (o, equivalence conductance):
daya hantar 1 gram ekivalen (grek) zat terlarut diantara
kedua elektroda yang berjarak 1 cm.
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Berat ekivalen:
berat molekul / jumlah muatan
1
A
G k
R
l
1000k
 
C
o
dan
1000
A
C
C = konsentrasi
= berat ekivalen/cm3
Dengan jarak antar elektroda l = 1 cm
Konstanta sel () didefinisikan:
1

A
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Sehingga berlaku:
1
1
0
0
0
G 
(C A A  C A A  .... C N N )
R 1000
Data perhitungan:
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1
1
G 
(C A 0A  C A 0A  .... C N 0N )
R 1000
Perhitungan
1.
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2.
Hitung daya hantar listrik larutan HCl
0,01M bila daya hantar ion untuk H+ =
350 dan Cl- = 76. Konstanta sel 0,2 cm-1.
Sebanyak 50 mL asam asetat 10-3M
diencerkan dengan 100 mL air. Tentukan
daya hantar listrik larutan tersebut bila
daya hantar ion CH3COO- = 40,9 dan
anggap konstanta sel = 1.
Perhitungan
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3. Hitung daya hantar campuran 10 mL HCl
0,01 M; 40 mL CH3COOH 0,01 M dan
100 mL air
Aplikasi
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Dalam berbagai titrasi asam basa:
1. Strong acid with a strong base
Aplikasi
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Dalam berbagai titrasi asam basa:
a. Asam kuat dg basa kuat (1-2)
Asam kuat dg basa lemah(1-3)
Aplikasi
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c. Asam lemah dengan basa kuat
d. Asam lemah dengan basa lemah
Aplikasi
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d. Campuran asam kuat – asam lemah dengan basa kuat
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