The end point is the point in a titration at which the indicator just changes colour, showing that the reaction is complete.
Malay: Takat akhir · Chinese: 终点
The end point is the point in a titration at which the indicator just changes colour, showing that the reaction between the acid and the alkali is complete. It is the signal to stop adding solution from the burette and to take the final reading. Because a titration is only as accurate as the moment you decide to stop, judging the end point sharply is one of the most important practical skills in this chapter.
A worked example shows the care needed. Titrating an alkali in the flask with acid from the burette, using phenolphthalein, you add acid steadily and swirl. As you near the end the pink fades slowly on each addition; you slow to one drop at a time until a single drop turns the whole flask permanently colourless. That drop marks the end point, and the burette reading taken there is the titre. Rushing past it by even a few drops overshoots and spoils the result.
The confusion to avoid is between the end point and the equivalence point. The equivalence point is the exact stage where the acid and alkali have reacted in their correct mole ratio; the end point is where the indicator we chose actually changes colour. With a well-chosen indicator the two are close enough to treat as the same, but they are not defined identically, and the exam rewards the precise wording “the indicator just changes colour”. A second slip is calling a temporary colour flash the end point, the change must be permanent on swirling.
Within this chapter the end point is what makes titration quantitative, linking the indicator to neutralisation and to the titre used in the calculation. Our teachers coach the drop-by-drop finish so your readings are consistent.
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