Difference Between Endpoint and Equivalence Point

Introduction: What is an Endpoint?

It is the stage of a titration at which the colour changes. Acids, as well as bases, are normally colourless liquids. As a result, an indicator that may alter the colour of the reaction medium with variations in pH is employed to indicate the end of the neutralisation reaction of an acid with a base. Phenolphthalein is a typical indicator used in acid-base processes. This indicator's colour changes between 8.3 (colourless) to 10.0. (pink). However, this indicator is ineffective for reactions occurring at low pH levels. As a result, the indication should be picked carefully.

It is not reached when all of the unknown has entirely interacted with the titrant. After self-indicators are used in processes, the endpoint is supplied when the entire amount of unknown has reacted with the titrant. As a result, the endpoint is equivalent to the equivalence point in this case. The half-reaction of 𝐶𝑟2𝑂2− to 𝐶𝑟3+, alters the hue of the medium from orange to green. This is because 𝐶𝑟6+ in the aqueous solution is orange while 𝐶𝑟3+ in the aqueous phase is green. As a result, this huge shift is considered the reaction's endpoint.

What is the Equivalence Point?

The Equivalence Point (Eq. point) is the exact point at which the chemical reaction in a titration mixture comes to a stop. Titrations are frequently used to evaluate the concentration of a chemical in a liquid. If the material is known, we can employ a known concentration of a titrant that can react with the chemical. Since the titrant's exact molarity is known, it is referred to as a standard solution.

Examine the reaction of sodium hydroxide with hydrochloric acid as an example. This is a base-acid reaction. As a concentration titrant, we can use either sodium hydroxide or hydrochloric acid. The titrant is put in the burette and then progressively introduced to the titrant/analyte reaction mixture until colour appears. Because sodium hydroxide $\mathrm{(NaOH)}$ and hydrochloric acid $\mathrm{(HCl)}$ are not self-indicators, an indicator should be utilised. The point at which the colour changes is considered the titration's endpoint. However, this is not the reaction's equivalence point (eq. point).

The equivalency point (eq. point) in this case is the moment at which all hydrochloric acid $\mathrm{(HCl)}$ molecules have interacted with sodium hydroxide $\mathrm{(NaOH)}$. The moles of the titrant should be equivalent to the moles of the unknown analyte in this case.

Titration Technique of Analytical Chemistry

Titration is a typical lab procedure used to evaluate the concentration of unknown solutions using known concentration solutions. In the titration procedure, a known concentration solution is known as the titrant, whereas an unknown concentration solution is known as the analyte. Titrimetric and volumetric analysis (VA) are additional terms for it. Often, the process is performed by gradually introducing a standard solution of titrating reagent out of a burette, which is a long measuring tube with a stopper as well as a delivery tube at the bottom end. The liquid from the burette is halted when the equivalency point (Eq. point) is reached.

Titration is a method of quantitative analysis (QA) that uses known concentration solutions to determine the unknown concentration of a known analyte. It is a volumetric analysis (VA) since volume measurement is important. It is derived from the French word 'titre,' which means "a measure of suitability or purity." Volumetric analysis (VA) 1𝑠𝑡 appeared in the late 1800s. It is a common lab technique. It is a sort of wet chemical analysis, often known as titrimetry. Acid-base titration, complexometric titration, precipitation along with redox titration (oxidation-reduction titration) are the types of titration procedures used in analytical chemistry.

Difference Between Equivalence Point and Endpoint

Endpoint	Equivalence Point (Eq. Point)
It is a titration step in which the hue or intensity of the solution changes to mark the completion of the titration.	The equivalence point (eq. point) is the titration step at which the concentrations of titrate with titrant are chemically equal.
The termination of the reaction emerges soon after it reaches the equivalence point (eq. point). In certain circumstances, depending on the pH, the endpoint, as well as equivalence point (eq. point), may happen simultaneously.	The equivalency point (eq. point) is often located a few milliseconds before or around the endpoint.
A chemical process has just 1 endpoint. The presence of the endpoint signifies that no more chemical reactions will occur.	A single chemical reaction may have several equivalency points. This situation is most visible in polyprotic acids with a high concentration of hydroxyl $\mathrm{(OH)}$ ions.
Weak acids only have one endpoint.	Weak acids have a high no. of equivalences.
It is always signalled by a change in the hue or intensity of the solution.	A change in hue may not always signal the equivalence point (eq. point).

Conclusion

Titration is an analytical chemistry method used to identify the amounts of acids, bases, reductants, oxidants, as well as other substances. An equivalence point (eq. point) is the stage at which the additional titrant is chemically identical to the sample analyte. The endpoint is the point where the colour of the solution changes. The major difference between equivalence (eq. point) versus endpoint is that the equivalence point (eq. point) is where the chemical process ends, while the endpoint is where the colour change happens in a system.

FAQs

1. What is the distinction between primary versus secondary standards?

A material is regarded as a primary standard if it has a high level of purity, is stable as well as unaffected by air, does not acquire or lose moisture in the air, is easily soluble, as well as its solution in water remains steady over time.A drug that lacks the aforementioned properties is referred to be a secondary standard chemical. Primary standards include crystalline oxalic acid, anhydrous $\mathrm{Na_{2}Co_{3}}$, and Mohr's salt, among others.

2. What is a typical solution? Why does the burette but also pipette needs to be washed with the liquid they are loaded with?

A typical solution has 1 gram-equivalent of the solutes per litre. The symbol one 𝑁 represents this. The burette but also pipette are washed with the liquid they are loaded with to eliminate any material that may adhere to their sides thus decreasing the volume of liquids to be received in them.

3. What species are present at the point of equivalence (eq. point)?

At the point of equivalency (eq. point) in acid-base titrations, salt plus water is evident.

4. Why are there 2 equivalence points (eq. points) for diprotic acids?

There are 2 equivalency points (eq. points) for diprotic acids. This is because the 2 ionising hydrogens (𝐻) do not dissolve from the acid simultaneously.

5. Is endpoint synonymous with neutralisation?

No. The neutralisation reaction is complete at the equivalence point (eq. point). Endpoint refers to the conclusion of the titration process or the signal of reaction accomplishment.