Science is a complex system that gives an insight of the world, insight of things that cannot be seen with bare eyes. Things are more complicated and complex as compared to what is visible to a normal person. Science gives reasoning for several things that are not an abstract form but proven practically in several ways.
Titration in chemistry is a method used for measuring the concentration of an unknown solution that reacts with a solution of known concentration. Titration is important for pharmaceutical companies. Solution of known concentration is called an analyte and a solution of unknown concentration is known as titrant.
The process of titration involves several terms other than analyte and titrant, like pipette, brutte, end point, equivalence point, etc..
Endpoint vs Equivalence Point
The main difference between endpoint and equivalence point is their occurrence. End point and equivalence point are different stages in the titration method, they have a lot of differences.
Comparison Table Between Endpoint and Equivalence Point
(in Tabular Form)
| Parameters of Comparison | Endpoint | Equivalence Point |
|---|---|---|
| Occurrence | Occurs after equivalence point. | Occurs before endpoint. |
| Frequency of occurrence | Occurs only one time. | Can occur more than one time. |
| Indication of occurrence | It is obtained when titration is complete. | It does not indicate the completion of titration. |
| Completion of reaction | Does not indicate complete reaction of analyte and titrant. | Does indicate complete reaction of analyte and titrant. |
| Change in color indicates | Endpoint reached | Approximation of equivalence point |
What is Endpoint?
An endpoint is a point at which the indicator changes its colour due to change in pH level. This happens when trident and analyte are mixed together in the process of titration.
The endpoint is considered as an ideal point for completion of titration. Endpoint is an intermediate point and not necessarily where the reaction ends. It comes after the equivalence point. It is the stage where indicators change its color and results can be derived.
There is only one endpoint in case of weak acids. When the endpoint is reached in titration it is often indicated with change in color of the solution. Once the solution starts changing the color, it will persist for 30 seconds.
When more base is added to titrant’s solution pH level changes which would become more basic and the solution changes the colour usually with indicator when titrant’s solution turns pink, which implies endpoint has been reached. In some cases endpoint and equivalence point can be reached at the same time as well. Although both are different but endpoint is sometimes reached with an equivalence point
What is Equivalence Point?
Equivalence point is the point where the amount of titrant added is just enough to completely neutralise the analyte solution.
Equivalence point in titration specifically in acid- base titrations , mole of base is equal to mole of acid and indicates that the solution contains only salt and water.
If the base is strong and acid is relatively weak then it produces salt and weakly alkaline during the process of titration, which results in pH greater than 7.
Equivalence point is also known as a stoichiometric point. The process of reaching equivalence point involves change in pH level, conductivity change, temperature change, formation of precipitate,etc..
To get the same equivalence point as the endpoint, then it is important that pH of indicator should match the pH at equivalence.
Main Differences Between Endpoint and Equivalence Point
- Endpoints can be reached with or after the point of equivalence.
- Equivalence point can be multiple in number during titration but the endpoint is the one point and does not occur frequently.
- Endpoint may or may not be the end of titration but equivalence is the complete end of titration after resulting in change of color of solution.
- Endpoint is indicated when there is change in color of solution but in case of equivalence point change in color of solution may or may not be visible.
- Equivalence point is reached when analyte has completely reacted with titrant whereas, endpoint does not always indicate that analyte has completely reacted with titrant.
Conclusion
Endpoint and equivalence points are two different and important stages of titration. Endpoint and equivalence point are indicated by change in color and change in pH level.
Titration is done in order to determine the concentration of any solution, mainly basic solution.it is done by mixing known concentration(acid) to an unknown solution and neutralising it.
Equivalence and endpoint are somewhere dependent on each other. As when without reaching an equivalent point endpoint cannot be reached. And without endpoint titration will not be completed.
Endpoint and equivalence points indicate successful titration. Being equivalent to each other indicates the perfect mixture of solutions (analyte and titrant).
References
- https://onlinelibrary.wiley.com/doi/abs/10.1002/sim.985
- https://www.sciencedirect.com/science/article/pii/S0008622309007854