277
The Carbonate System
E* = E – k log[{(V – V 2 )/(V 0 + V)} N HCl ]
(7.100)
The average E* can be used to refine the calculations. For the data shown, TA = 2.237 ±
0.007 mmol kg –1 , TCO 2 = 2.023 ± 0.013 μmol kg –1 , pH SWS = 7.731 ± 0.019, and E* = 407.6 ± 1.1 mV.
To make more accurate calculations, it is necessary to make corrections for side reactions. The modified F 2 ′ is given by
F 2
0.00 0.01 0.02 0.03 0.04 0.05 0.06
HCl Volume (cm
3
)
1.9
2.0
2.1
2.2
2.3
V 2 = 1.931 ± 0.005 cm
3
Figure 7.9
The Gran function F 2 as a function of the volume of HCl added during the titration of seawater.
F 1
0.1
0.2
0.3
0.4
0.5
0.6
HCl Volume (cm
3
)
0.30
0.35
0.40
0.45
0.50
0.55
0.60
0.65
0.70
V 1 = 0.237 ± 0.005 cm
3
Figure 7.10
The Gran function F 1 as a function of the volume of HCl added during the titration of seawater.