Titration theory – Hanna Instruments HI 903 User Manual
Page 195
3
TITRATION THEORY
Contents
1
GENERAL REVIEW OF TITRATION THEORY............................................................................. 5
1.1
Introduction to Titrations .................................................................................................. 5
1.2
Uses of Titrations .............................................................................................................. 5
1.3
Advantages and Disadvantages of Titrations .................................................................... 6
2
TYPES OF TITRATION ........................................................................................................... 7
2.1
Titrations According to The Measurement Method ............................................................. 7
2.1.1
Amperometric Titrations .......................................................................................................... 7
2.1.2
Potentiometric Titrations ......................................................................................................... 7
2.1.3
Spectrophotometric Titrations .................................................................................................. 8
2.2
Titrations According to The Reaction Type ........................................................................ 9
2.2.1
Karl Fischer Titration ............................................................................................................... 9
2.2.1.1 History of Karl Fischer Titrations ............................................................................................... 9
2.2.1.2 Visual Indication of Karl Fischer Titrations ................................................................................. 10
2.2.1.3 Electrometric Indication of Karl Fischer Titrations ....................................................................... 10
2.2.2
Acid - Base Titrations .............................................................................................................. 11
2.2.3
Argentometric Titrations .......................................................................................................... 12
2.2.4
Complexometric Titrations ....................................................................................................... 12
2.2.5
Ion Selective Titrations ............................................................................................................ 13
2.2.6
Non-aqueous Solvent Acid - Base Titrations ............................................................................... 13
2.2.7
Precipitation Titrations ............................................................................................................ 14
2.2.8
Redox Titrations ..................................................................................................................... 14
2.3
Titrations According to The Titration Sequence ................................................................ 15
2.3.1
Back Titrations ....................................................................................................................... 15
2.3.2
Multiple End Point Titrations .................................................................................................... 15
3
INTRODUCTION TO TITRATION APPARATUS AND TYPICAL TITRATION PROCEDURE ................ 17
3.1
Manual Titration ............................................................................................................... 17
3.2
Automatic Titration .......................................................................................................... 18
4
TITRATION RESULTS .......................................................................................................... 19
4.1
Accuracy .......................................................................................................................... 19
4.2
Repeatability .................................................................................................................... 19
4.3
Sources of Error ............................................................................................................... 19
4.3.1
Sampling Errors ..................................................................................................................... 19
4.3.2
Errors with Titrant and Standard .............................................................................................. 19
4.3.2.1 Preparation Errors .................................................................................................................. 19
4.3.2.2 Dispensing Errors ................................................................................................................... 20
4.3.3
Chemical Reaction Errors .................................................................................................. 20
4.3.4
End Point Determination Errors ........................................................................................ 20
5
CALCULATIONS .................................................................................................................. 21
5.1
Equations Used in Karl Fischer Titrations ........................................................................... 21
5.1.1
Calculation of water content as % mass from samples measured by mass .................................... 21
5.1.2
Calculation of water content as % mass from samples measured by volume ................................. 21
5.1.3
Calculation of water content as % volume from samples measured by volume .............................. 21
5.1.4
Calculation of water content subtracting Background Drift Rate .................................................... 21
5.1.5
Calculation of water content in external dissolutions samples ...................................................... 22
5.1.6
Calculation of water content in external extraction samples ......................................................... 22
5.1.7
Calculation of water content in gaseous samples ....................................................................... 22
5.1.8
Calculation of Titer (water equivalent of the titrant) using sodium tartrate dihydrate containing 15.66% water
by mass................................................................................................................................. 22
5.1.9
Calculation of Titer (water equivalent of the titrant) using water standards ................................... 23
5.2
Equations Used in Titrations ............................................................................................. 23
5.2.1
Sample Calculation ................................................................................................................. 23
5.2.2
Standardize Titrant ................................................................................................................. 23
5.2.3
Blank Titration ........................................................................................................................ 24
5.2.4
Multiple End Point Titration ...................................................................................................... 24
5.2.5
Back Titration ......................................................................................................................... 25
6
GLOSSARY ........................................................................................................................ 26