The key difference between the equivalence point and the neutralization point in a titration lies in what each point represents: the equivalence point signifies stoichiometric completion, while the neutralization point specifically refers to a pH of 7.
Understanding the Equivalence Point
The equivalence point is the point in a titration where the amount of titrant added is exactly enough to react completely with the analyte according to the reaction stoichiometry. In simpler terms, it's when the moles of acid equal the moles of base in the reaction mixture, based on the balanced chemical equation.
- Stoichiometric Ratio: The equivalence point is determined by the mole ratio of reactants.
- Chemical Completion: It marks the theoretical point where the reaction is complete.
Defining the Neutralization Point
The neutralisation point (or neutralization point) is defined as the point during a titration when the pH of the solution becomes exactly 7. This is the point where the solution is considered chemically neutral.
- pH Criterion: The defining characteristic is a pH value of 7.
- Neutrality: Represents a state where hydrogen ion concentration equals hydroxide ion concentration in pure water at 25°C.
Key Difference Explained
While the terms are often used interchangeably in simple titrations, especially strong acid-strong base reactions where the equivalence point does occur at pH 7, they are not always the same.
As noted in the provided reference: "The neutralisation point of a titration is the point at which just the right amount of titre has been added to make the pH of the solution 7 (neutral)." However, the reference also highlights, "if a strong acid is titrated with a weak base, at the equivalence point, the solution produced doesn't have a pH of 7."
This is because the salt formed from a strong acid and a weak base undergoes hydrolysis, producing an acidic solution (pH < 7) at the stoichiometric equivalence point. Similarly, the equivalence point of a weak acid-strong base titration will be at a pH > 7 due to the hydrolysis of the conjugate base. Only in the titration of a strong acid with a strong base is the equivalence point precisely at pH 7, coinciding with the neutralization point.
Summary of Difference:
| Feature | Equivalence Point | Neutralisation Point |
|---|---|---|
| Definition | Stoichiometric completion of the reaction | Point where the solution's pH is exactly 7 |
| Determined by | Moles of reactants based on balanced equation | Solution pH value |
| Coincidence | Coincides with neutralization point only for strong acid/strong base titrations | Coincides with equivalence point only for strong acid/strong base titrations |
| pH Value | Can be < 7, = 7, or > 7 depending on reactants | Always = 7 by definition |
In essence, the equivalence point is a theoretical point based on the stoichiometry of the reaction, while the neutralization point is an experimental point based on reaching a specific pH value (7).
