Difference Between Acid-Base Titration and Redox Titration

Key Difference – Acid-Base Titration vs. Redox Titration

In general,titrationsare used to determine the concentration of an unknown solution (analyte). The most commonly used two titrimetric methods are acid-base titrations and redox titrations. Thekey differencebetween acid-base titrations and redox titrations之间发生的反应的本质吗the titrant and the analytein the titration. In acid-base titrations, a neutralization reaction takes place and in redox titrations, a redox reaction takes place (an oxidizing reaction and a reduction reaction). The use of indicators is the most commonly used method of determining theendpointof the reaction.

What is an Acid-Base Titration?

In acid-base titrations,an acid(acidic titrations) or abase(basic titrations) is used as the titrant. Examples of acids used in acidic titrations are H₂SO₄, HCl, or HNO_3.Mostly used basic titrants are NaOH, K₂CO₃or Na₂CO_3.Acid-base titrations can be classified as follows depending on the strength of the acid and the base.

1. Strong acid – strong base titrations
2. Strong acid- weak base titrations
3. Weak acid – strong base titrations
4. Weak acid – weak base titrations

In most of the acid-base titrations, indicators are used to determine the end point of the reaction. Different indicators are used depending on the type of the titration as mentioned above.

What is a Redox Titration?

A redox titration involves a redox reaction. Redox reaction has two reactions; anoxidation reaction and a reduction reaction. Both oxidation and reduction processes take place at the same time where allowing us to determine the completion of the reaction. This is also known as the end point of the titration. This can be determined in several ways; using indicatorelectrodes, redox indicators (the indicator produces a different color at oxidation-reduction state), and non-redox indicators (indicator produces a color when an excess amount of titrant is added).

What is the difference between Acid-Base Titration and Redox Titration?

Nature of the reaction:

Acid-Base Titration:An acid-base titration involves a neutralization reaction between the analyte (the solution with the unknown concentration) and the acidic or basic titrant.

Redox Titration:A redox reaction involves an oxidation and reduction reaction between the analyte and the titrant. There is no such a rule that component oxidizes and which one reduces. Either analyte or the titrant oxidizes, and the remaining component reduces accordingly.

Determination of the end point:

Acid-Base Titration:一般来说,酸碱指示剂,酸度计或conductance meter is used to determine the end point of an acid-base titration.

Redox Titration:The most commonly used methods of determining the end point of a redox reaction are using apotentiometeror a redox indicator. But, most frequently either the analyte or the titrant produces a color at the endpoint. So that, additional indicators are not required in those cases.

Examples:

Acid-Base Titration:

Type	Reaction (Indicator)
Strong acid – strong base titration	HCl + NaOHàNaCl + H2O(Phenolphthalein /Methyl orange)
Strong acid – weak base titration	HCl + NH3à NH3Cl (Methyl orange)
Weak acid – strong base titration	CH3COOH + NaOHà CH3COONa + H2O (Phenolphthalein)
Weak acid –weak base titration	CH3COOH + NH3àCH3COO–+NH4+(No suitable indicators)

Redox Titration:

2 KMnO₄+ 5 H₂C₂O₄+ 6 HCl→2 MnCl₂+ 2KCl + 10 CO₂+ 8 H₂O

(+7) (+3) (+2) (+4)

In the above reaction, permanganate is reduced while oxalic acid is oxidized. When the reaction completes, the purple color of permanganate changes into colorless.

KMnO₄+ 5FeCl₂+8HCl→5FeCl₃+MnCl₂+KCl+4H₂O
(+7) (+2) (+3) (+2)

Image Courtesy:

1.Titration of weak acid with strong baseBy Quantumkinetics (Own work) [CC BY 3.0], via Wikimedia Commons

2. “Winkler Titration Prior Titration” by Willwood [CC BY-SA 3.0] via Commons