Citra Angraini

Indri Savitri

Yuliana

Group 13

Multiplication Equations (2:56) with z+ produces 2 = - v z - z + and multiplication Equation (2:56) with z – generating v-z -

2 = -v+ z+ z -.

Summing both produce:

)()(v 22 vvzzvvzzzvz (2.57)

By using the value - the value of SI for = 78.38, kg / m3 for water at 25 ° C and 1 atm into equation (2:58) then:

A = 1.1744 (kg / mol) 1/2,

B = 3.285 x 109 (kg / mol) 1 / 2m-1.

Because negative. Debye-Huckel equation substitution (2.50) into equation (2:54) followed by the use of equation (2:57) yields:

2/1

2/1

1ln

m

m

BaI

AIzz

(2.58)

With mensubsitusikan value - the value of A and B into Equation (2:58) and dividing A by 2.3026 to convert it into a log shape, we obtain:

2/1

2/1

)/)(/(328,01510,0log

om

o

om

mIAa

mI

zz

(2.59)

For very dilute solutions, very small and the second term in the denominator of equation (2:59) is negligible compared to 1. Therefore, for very dilute solutions:

2/1log mAIzz (2.60)

and for very dilute solutions with solvent water at 25 ° C:

2/1)/(510,0log om mIzz

Equation (2.60) is called the Debye-Huckel law limited (Debye-Huckel Limiting Law, DHLL), because it applies only to the limit of infinite dilution.

Application of Equilibrium Constants Determination DHLL on Ion

Equilibrium constants Weak Acid

Determination of the equilibrium constant can help calculation of activity coefficients and vice versa. The procedure can be illustrated with reference to the dissociation of acetic acid, CH3COOH CH3COOH(aq) H

+(aq) + CH3COO-

(aq)

Equilibrium constants is given by:

uCOOHCH

COOCHHa

COOHCH

HCOOCHa

K

a

aaK

3

3

3

3

(2.61)

With mengganti by and by taking the logarithm Equation (2.61) becomes:

log2loglog

3

3 oKCOOHCH

COOCHH

which we can then write:

log2log

1log

2oK

c (2.62)

If the only solution containing acetic acid, ionic strength, given by:

cccI 22 )1(12

1

Further usual plot left side of equation (2.62) for = 0 gives the price Ko, as shown in Figure 2.14.

The results of solubility constant time

Now we will look at an example, in this case the solubility product of silver chloride, that disclosure would be more accurate to liveliness.AgCl(s) ↔ Ag+

(aq) + Cl-(aq)

101010

2

log2loglog ClAgK

ClAg

ClAgaaK

sp

ClAgsp

for a solution that does not have a namesake ions, solubility is:

101010

10102

10

loglog2

1log

log2loglog

sp

sp

Ks

Ks

ClAgs

Extrapolation to zero ionic strength, giving the log price = 0, and provide price ½ log Ksp obtained as a cut point.