Titra
Lab
®
TitraLab 870 Reference Manual
Page 267
4. Back titration
The back titration is performed in two steps:
- reaction of the excess reagent with the sample : z w Excess
- reaction of the titrant with the excess of reagent : x y titrant
According to the definition of stoichiometric coefficients, z is equal to y.
The calculation is performed in equivalent. If the concentrations are not in equivalent per litre,
then the stoichiometric coefficients are used. When the titration starts, the excess reagent has
a number of equivalent equal to : Ve * Ce * c' , with:
The reaction of the excess reagent with the titrant gives : Vtit * Ctit * c'', with:
Then, the sample concentration is calculated as follows:
With:
Ce
c’ value
eq/l
1
meq/l
0.001
mol/l
z
mmol/l
0.001 * z
Ctit
c’’ value
eq/l
1
meq/l
0.001
mol/l
x
mmol/l
0.001 * x
“C
smp
”
“c” if “Vs” in “ml”
eq/l = N
1
meq/l
1000
mol/l = M
1 / w
mmol/l
1000 / w
g/l = mg/ml
M
smp
/ w
mg/l
M
smp
* 1000 / w
mol
Vs * 0.001 / w
mmol
Vs / w
g
M
smp
* Vs * 0.001 / w
mg
M
smp
* Vs / w
µg
M
smp
* Vs * 1000 / w
Csmp
V
e
Ce
c
′
Vtit
Ctit
c
″
×
×
–
×
×
Vs
--------------------------------------------------------------------
c
×
=
Summary of Contents for TitraLab 870
Page 1: ...TitraLab 870 pH EP IP EC ISE Titration Workstation Reference Manual D21T060...
Page 2: ...D21T060 Printed by Radiometer Analytical SAS 2008 02F...
Page 22: ...TitraLab TitraLab 870 Reference Manual Page 22...
Page 23: ...Practical examples s...
Page 24: ......
Page 32: ...TitraLab TitraLab 870 Reference Manual Page 32...
Page 40: ...TitraLab TitraLab 870 Reference Manual Page 40...
Page 41: ...Glossary...
Page 42: ......
Page 255: ...Appendixes...
Page 256: ......
Page 258: ...TitraLab TitraLab 870 Reference Manual Page 258...
Page 262: ...TitraLab TitraLab 870 Reference Manual Page 262...
Page 280: ...TitraLab TitraLab 870 Reference Manual Page 280...
Page 286: ...TitraLab TitraLab 870 Reference Manual Page 286...