Potentiometric Determination of Oxalic Acid non Aqueous

Potentiometric Determination of Oxalic Acid non-Aqueous

Equipment

Potentiometer = 751 GPD Titrino / Titroprocessor
Electrodes = 6.0103.100 pH glass electrode; input 1
6.0726.100 Ag/AgCl double junction reference electrode (LiCl sat. in ethanol)

Reagents

c(TBAOH) = 0.1 mol/L; D0
TBAOH = Tetrabutyl ammonium hydroxide

Sample

2 mL c(C₂H₂O₄) = 0.1 mol/L; HOOC-COOH
25 mL ethanol

Remarks

Calculations:

Oxalic=EP2*C01/C02/C00;3;mol/l

Oxalic = concentration of oxalic acid in mol/L
C01 = concentration of titrating agent (0.1 mol/L)
C02 = factor for “normality“ (2)
· Compare also titration in aqueous medium, application No. 1-4

Answer

Oxalic = 4.221 x 0.1 / 2 / 2 = 0.106 mol/L

EP1 = 2.048 mL
EP2 = 4.221 mL
C00 = 2.00 mL

Literature

Metrohm’s Teachware on CD-ROM

Method documentation

'pa
751 GPD Titrino 15215 751.0010
DET U OxalicNA
parameters
>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 …6 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 OxalicNA
>calculations
Oxalic=EP2*C01/C02/C00;3;mol/l
C00= 2.0
C01= 0.1
C02= 2
------------
'fr
751 GPD Titrino 15215 751.0010
U(init) 341 mV DET U OxalicNA
smpl size ...2.0 ml
EP1 …2.048 ml… 152 mV
EP2 …4.221 ml… -130 mV
Oxalic …0.106 mol/l
stop V reached
============
'cu
751 GPD Titrino 15215 751.0010
start V 0.000 ml DET U OxalicNA
1.0 ml/div dU=200.0 mV/div

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