9
TITRATION THEORY
2.2
Titrations According to The Reaction Type
2.2.1 Acid-Base Titrations
Acid–base titrations are the most common type of titrations. They are based upon a reaction
between an acid and a base, a stoichiometric neutralization, or the exchange of protons.
Virtually all acid-base titrations are carried out using a strong acid or a strong base as the
titrant. The endpoint of a titration carried out with a weak acid or a weak base would be
difficult to detect due to a small change in pH at the equivalence point.
Chemical indicators can be used to determine the endpoint. The indicator will change color
to signify that the end of the titration has been reached. The color of the indicator is dependent
upon the concentration of ions in the solution. An acid-base indicator is composed of a
conjugate weak acid-weak base pair, where the two forms exhibit different colors depending
on the pH of the solution. For an indicator, the acid ionization constant Ka is usually written
as: [H
3
O
+
][In
–
]
Ka= [HIn]
HIn is the acid form of the indicator and
In
–
is the base form. At the center of the
change region, the ratio of [In
–
] to [HIn]
is one, [H
3
O
+
]=Ka and pH=pKa. The color
change region is usually ±1 pH unit around
this point. Table 1 contains a list of some
aqueous acid-base chemical indicators, as
well as the pH range, the pKa and the
expected color (acid and base form). When
choosing the proper indicator you should
select one that has a pKa as close to the
endpoint of the titration.
When chemical indicators are not suitable,
a potentiometric pH titration can also be
used. The pH of the solution is plotted
versus the volume of titrant added. Figure
4 shows a traditional strong acid-strong
base titration curve. The graph shows the
Figure 3
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Table 1
Summary of Contents for HI 902 Color
Page 6: ...6 QUICK START GUIDE TITRATOR CONNECTIONS Front View Rear View sale ponpe com www ponpe com ...
Page 18: ...18 QUICK START GUIDE QS 902C 10 10 sale ponpe com www ponpe com ...
Page 22: ...1 2 INTRODUCTION sale ponpe com www ponpe com ...
Page 24: ...1 2 INTRODUCTION sale ponpe com www ponpe com ...
Page 26: ...2 2 SETUP sale ponpe com www ponpe com ...
Page 36: ...3 2 USER INTERFACE sale ponpe com www ponpe com ...
Page 44: ...4 2 GENERAL OPTIONS sale ponpe com www ponpe com ...
Page 100: ...5 44 METHODS sale ponpe com www ponpe com ...
Page 102: ...6 2 TITRATION MODE sale ponpe com www ponpe com ...
Page 106: ...6 6 TITRATION MODE sale ponpe com www ponpe com ...
Page 138: ...8 2 AUXILIARY FUNCTIONS sale ponpe com www ponpe com ...
Page 148: ...9 2 MAINTENANCE PERIPHERALS sale ponpe com www ponpe com ...
Page 160: ...A1 2 APPENDIX 1 sale ponpe com www ponpe com ...
Page 164: ...A2 2 APPENDIX 2 sale ponpe com www ponpe com ...
Page 170: ...A3 2 APPENDIX 3 sale ponpe com www ponpe com ...
Page 174: ...A3 6 APPENDIX 3 sale ponpe com www ponpe com ...
Page 176: ...A4 2 APPENDIX 4 sale ponpe com www ponpe com ...
Page 184: ...A5 2 APPENDIX 5 sale ponpe com www ponpe com ...
Page 193: ...A5 11 APPENDIX 5 ...
Page 194: ...A5 12 APPENDIX 5 MAN902C 10 10 ...
Page 196: ...1 2 INTRODUCTION ...
Page 224: ...2 TITRATION THEORY sale ponpe com www ponpe com ...
Page 248: ...26 TITRATION THEORY Titr THEORY 901 902 04 10 ...
