[jubba]

when titrating acetic acid with NaOH using phenophthalein as the indicator what is the endpoint (EDIT)
 
One of my sources says when one drop of NaOH cause the pink to last for more than a second, whilst swirling. The other just says until a persistant very light pink is observed.

Which one is right and will CO2 in the air significantly affect the endpoint colour.

[Alberto_Kravina]

when titrating acetic acid with NaOH using phenophthalein as the indicator what is the indicator

One of my sources says when one drop of NaOH cause the pink to last for more than a second, whilst swirling. The other just says until a persistant very light pink is observed.

When you add NaOH without shaking the Erlenmeyer Flask you'll observe a violet color that vanishes after a few seconds. The best wasy to catch the endpoint is to add NaOH drop by drop (and - of course, shaking the flask carefully) until the color changes to pink.

will CO2 in the air significantly affect the endpoint colour.

Not at all, I think.... It never happened to me

[lavoisier]

Actually, when phenolphtalein turns pink the pH might be quite high (say >9), so if you wait too long and/or swirl the solution too vigorously, some CO2 can be absorbed, making it turn colourless again.

In practice, however, the end point is when you see the pink colour persist after all the solution has been thoroughly mixed (i.e. when it's homogeneous).

[jubba]

is the endpoint the same for NaoH vs HCl

[Borek]

Read about titration curves calculation - last three paragraphs contain answer.

[irish_lass]

The end point for NaOH and acetic acid is defined as the first permanent pink colour.ie it is just light pink bt when u swirl the flask the pink is still visable!
Also for NaOH and HCl you use methyl-orange indicator and the colour change is from yellow-pink! Hope this helps!

[Borek]

Also for NaOH and HCl you use methyl-orange indicator and the colour change is from yellow-pink! Hope this helps!

Most important thing is not indicator used nor color change, as these things can be changed. What is important is equivalence point pH.