Determination of Strong Acid with Potentiometric Methods

Determination of Strong Acid with Potentiometric Methods

Equipments

Potentiometer = 751 GPD Titrino / Titroprocessor
Electrodes = 6.0232.100 combined pH glass electrode; input 1

Reagents

c(NaOH) = 0.1 mol/L; D0

Sample

2 mL c(HCl) = 0.1 mol/L
50 mL dist. Water

Remarks

Calculations:

C(acid) = EP1*C01*C37/C00 ; 3 ; mol/L

c(acid) = concentration of acid in mol/L
C01 = concentration of titrating agent (0.1 mol/L)
C37 = titer of titrating agent (1.0013 common variable of “Tit.NaOH“)
Carbonate may be detected separately if present!

Answer

C(acid) = 1.996 x 0.1 x 1.003 / 2.00 = 0.100 mol/L

EP1 = 1.996 mL
C00 = 2.00 mL

Literature
Metrohm’s Teachware on CD-ROM

Method documentation

751 GPD Titrino
DET pH Acid
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...4 ml
stop pH...OFF
stop EP...9
filling rate max...ml/min
>statistics
status:...OFF
>evaluation
EPC...5
EP recognition:... all
fix EP1 at pH...OFF
pK/HNP:...OFF
>preselections
req.ident:...OFF
req.smpl size:...OFF
activate pulse:...OFF
------------
'fm
751 GPD...Titrino
DETpH... Acid
>calculations

c(acid)=EP1*C01*C37/C00;3;mol/l

C00= 2.00
C01= 0.1
C37= 1.0013
------------
'fr
751 GPD...Titrino
pH(init)...DET.pH.Acid...2.55
smpl size ...2.00 ml
EP1...7.72.mV...1.996 ml
c(acid)... 0.100 mol/l
stop V reached
============
'cu
751 GPD...Titrino
start V...DET.pH.Acid...0.000 ml
2.0 ml/div dpH=2.0/div
============