Which term marks the moment in a titration when the indicator changes colour?

Which term marks the moment in a titration when the indicator changes colour?

• A. Titration
• B. Endpoint
• C. Buffer region
• D. Indicator

Answer: (B)

The endpoint is the moment in a titration when the indicator changes colour. This colour shift happens because the solution’s pH has moved into the indicator’s transition range, and it’s deliberately chosen so that this colour change occurs near the equivalence point, giving a practical signal that the amount of titrant added is enough to reach (or closely approximate) the stoichiometric point where acid and base have reacted in equal moles. In theory, the exact chemical point is the equivalence point—when moles of acid equal moles of base—but the endpoint is the observable cue used in experiments. The other terms refer to different ideas: titration is the entire process, the buffer region is where pH changes slowly due to buffering, and an indicator is the dye that shows the colour change.

The endpoint is the moment in a titration when the indicator changes colour. This colour shift happens because the solution’s pH has moved into the indicator’s transition range, and it’s deliberately chosen so that this colour change occurs near the equivalence point, giving a practical signal that the amount of titrant added is enough to reach (or closely approximate) the stoichiometric point where acid and base have reacted in equal moles. In theory, the exact chemical point is the equivalence point—when moles of acid equal moles of base—but the endpoint is the observable cue used in experiments. The other terms refer to different ideas: titration is the entire process, the buffer region is where pH changes slowly due to buffering, and an indicator is the dye that shows the colour change.