Potentiometric Determination of the Na+ / Cl - in Isotonic Solution

Potentiometric Determination of the Na+ / Cl- in Isotonic Solution

Equipment
Potentiometer = 751 GPD Titrino / Titroprocessor
Electrodes = 6.0430.100 Ag Titrode; input 1

Reagents
c(AgNO3) = 0.1 mol/L; D0

Sample
5 mL sample solution (153 mmol/L Na+ / Cl-)
2 mL c(HNO3) = 2 mol/L
30 mL dist. water

Remarks
· Calculations:

Na+Cl-=EP1*C01*C02/C00;2;mmol/l

Na+Cl- = concentration of Na+ / Cl- in isotonic solution in mmol/L
C01 = concentration of titrating agent (0.1 mol/L)
C02 = factor for conversion mol/L Þ mmol/L (1000)

. Answer

Na+Cl- = 7.652 x 0.1 x 1000 / 5.00 = 153.04 mmol/L

EP1 = 7.652 ml
C00 = 5 mL

Literature
· Metrohm Application Bulletin No. 130: Chloride titrations with
potentiometric end-point indication.

Method documentation

'pa
751 GPD Titrino 15215 751.0010
DET U Na+Clparameters
>titration parameters
meas.pt.density… 4
min.incr. …10.0 ml
dos.rate max…. ml/min
signal drift …50 mV/min
equilibr.time …26 s
start V: …OFF
pause …0 s
dos.element:… internal D0
meas.input: …1
temperature… 25.0 °C
>stop conditions
stop V: …abs.
stop V …10 ml
stop U …OFF mV
stop EP …9
filling rate max…. ml/min
>statistics
status:…. OFF
>evaluation
EPC …5
EP recognition:… all
fix EP1 at U …OFF mV
pK/HNP: …OFF
>preselections
req.ident: …OFF
req.smpl size:… OFF
activate pulse: …OFF
------------
'fm

751 GPD Titrino 15215 751.0010
DET U Na+Cl-
>calculations

Na+Cl-=EP1*C01*C02/C00;2;mmol/l

C00= 5.0
C01= 0.1
C02= 1000
------------
'fr
751 GPD Titrino 15215 751.0010
U(init) 224 mV DET U Na+Clsmpl
size 5.0 ml
EP1 7.652 ml 49 mV
Na+Cl- 153.04 mmol/l
stop V reached
============
'cu
751 GPD Titrino 15215 751.0010
start V 0.000 ml DET U Na+Cl-
2.0 ml/div dU=100.0 mV/div
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