[triggy]

Hi, I need some clarification on the endpoint of a titration to solve this question.

Phenolphthalein was added to a solution of HNO3 that is being titrated with KOH. The question asks to approximate the endpoint of this titration. Does the endpoint occur when the pH indicator begins to change colour, so when the solution is a very light pink? Or does the endpoint occur when the colour of the solution is no longer changing?

Thanks.

[ARGOS++]

Dear triggy;

As you are titrating from the acid site, so it means as soon as you see a first steady pink color, according to:
           http://en.wikipedia.org/wiki/PH_indicator  

Good Luck!
                    ARGOS⁺⁺

[triggy]

Alright. Thank you.

[ARGOS++]

Dear triggy;

You 're welcome!   ─   Soon again.

Good Luck!
                    ARGOS⁺⁺

 P.S.: Thank you too!
.

[Borek]

It depends on several factors, but in this case first change in color. See

http://www.titrations.info/acid-base-titration-end-point-detection