Potentiometric Determination of the Hydrogen Peroxide

Potentiometric Determination of the Hydrogen Peroxide

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 sample
2 mL c(H2SO4) = 0.5 mol/L
0.1 g MnSO4*H2O (catalyst)
100 mL dist. Water

Remarks
Determination reaction:

5 H2O2 + 2 MnO4 ^- + 6 H+ .............2 Mn2+ + 5 O2 + 8 H2O

Sample preparation:

app. 1.2 g w(H2O2) ..0.30 (30%) in 100 mL c(H2SO4) = 0.5 mol/L

Calculations:

H₂O₂=EP1*C01*C02*C03*C04*C05/C00;2;%

H₂O₂ = fraction of H2O2 in %
C01 = concentration of titrating agent * titer (0.02 mol/L)
C02 = factor for “normality“ (5/2 = 2.5)
C03 = molecular mass of H2O2 (34.04 g/mol)

C04 = factor for conversion 1 mL...L* factor for % (0.001 * 100 = 0.1)
C05 = dilution factor (50)

Answer

H₂O₂= 4.348 x 0.002 x 2.5 x 34.04 x 0.1 x 50 / 1.2005 =30.80%

The start V in this method meets two purposes:
1. It speeds up the titration.
2. Mn2+ is generated which serves as catalyst for the reaction so there is no need to add Mn2+ separately.

Literature
Metrohm’s Teachware on CD-ROM

Method documentation

'pa
751 GPD Titrino 15215 751.0010

DET U H2O2
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 …1 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 …6 ml
stop U ….OFF mV
stop EP ….9
illing 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 H2O2
>calculations

H2O2=EP1*C01*C02*C03*C04*C05/C00;2;%

C00= 1.2005
C01= 0.02
C02= 2.5
C03= 34.02
C04= 0.1
C05= 50
------------
'fr
751 GPD Titrino 15215 751.0010
U(init) -225 mV DET U H2O2
smpl size ….1.2005 g
EP1 …..4.348 ml…. -501 mV
H2O2 ….30.80 %
============
'cu
751 GPD Titrino 15215 751.0010
start V 1.000 ml DET U H2O2
1.0 ml/div dU=100.0 mV/div