A rapid Method for the Determination of Iron (II) with Potentiometric

A rapid Method for the Determination of Iron (II) with Potentiometer

Equipment
Potentiometer = 751 GPD Titrino / Titroprocessor
Electrodes = 6.0431.100 Pt Titrode; input 1

Reagents
c(KMnO₄) = 0.02 mol/L; D0

Sample
2 mL c[(NH₄)₂Fe(SO₄)₂] = 0.1 mol/L, acidic solution
10 mL c(H₂SO₄) = 0.5 mol/L
40 mL dist. Water

Remarks
· Determination reaction:

5 Fe²⁺ + MnO₄^- + 8 H⁺ → 5 Fe³⁺ + Mn²⁺ + 4 H₂O

· Calculations:

Fe++=EP1*C01*C02/C00;2;g/l

Fe++ = concentration of Fe²⁺ in g/L
C01 = concentration of titrating agent * titer * “normality“ (0.02 * 1.000 * 5 = 0.1)
C02 = molecular mass of Iron (55.85 g/mol)

Answer

Fe++=2.065x0.1x55.85/2=5.77 g/L

EP1=2.065 mL
C00=2.000 mL

Literature
Metrohm’s Teachware on CD-ROM

Method documentation

'pa
751 GPD Titrino 15215 751.0010
DET U….Iron(II)
parameters
>titration parameters
meas.pt.density…. 4
min.incr. ….10.0 ml
dos.rate max…. ml/min
signal drift… 10 mV/min
equilibr.time… 52 s
start V:… abs.
start V… 0.5 ml
dos.rate max…. ml/min
pause… 0 s
dos.element:… internal D0
meas.input:… 1
temperature …25.0 °C
>stop conditions
stop V:… abs.
stop V …4 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 Iron(II)
>calculations
Fe++=EP1*C01*C02/C00;2;g/l
C00= 2.0
C01= 0.1
C02= 55.85
------------
'fr
751 GPD Titrino 15215 751.0010
U(init)… -136 mV DET U... Iron(II)
smpl size… 2.0 ml
EP1… 2.065 ml… -476 mV
Fe++ ….5.77 g/l
stop V reached
============
'cu
751 GPD Titrino 15215 751.0010
start V.... 0.500 ml DET U.... Iron(II)
1.0 ml/div dU=200.0 mV/div
============
'dv
751 GPD Titrino 15215 751.0010
start V 0.500 ml DET U Iron(II)
1.0 ml/div ERC=20.0/div
==========