Question

Explain the difference between the terms equivalence point and endpoint. Do not simply define each term, explain what makes them different as well.

Answer 1

1. The equivalence point in a titration is the point at which the added titrant is chemically equivalent completely to the analyte in the sample. End point is the point where the indicator changes its colour. 2. Equivalence point comes before the end point. 3. To get the same equivalent point as the end point, the pH of the indicator should match the pH at the equivalence. A. In equivalence point the moles of acid are chemically equivalent to that of the based 5. End point is the point of completion I of the reaction between two solutions. 6. Equivalence point gives the point where the unknown analyte has completely rearted with the titrant. Endpoint does not always give the point where the unknown analyte has completely reacted with the titrant.

Example:-

Here, the equivalence point is the point where all HCl molecules have reacted with NaOH (or the point where all NaOH molecules have reacted with HCl). Here, the moles of titrant should be equal to the moles of the unknown analyte. A - Equivalence point B - End point 0 x Y Z Volume of base added (ml) Figure 1: Titration curve for a titration of an acid with a base