# Acid-base titration: Unknown base in burette or flask?

While finding the concentration of $$\ce{NaOH}$$ via titration with $$\pu{0.05M}$$ Oxalic acid solution (in our lab) we put NaOH in the burette whereas added phenolphthalein to oxalic acid in titration flask. But in this video the demonstrator does just opposite ( i.e., $$\ce{NaOH}$$ in flak with phenolphthalein). I am confused in deciding which one might be correct. My view is that either would do the job but I need some clarification.

• Both are perfectly correct methods as long as the volume measurements are accurate. – M. Farooq Nov 1 '19 at 16:12
• @M.Farooq - I disagree. It is easier to detect the change from colorless to colored. So, if possible, the titrant should be a base when phenolphthalein is the indicator. – MaxW Nov 1 '19 at 19:41
• No matter what you do students will always come to you holding the flask asking if this is the right end-point :-) For a skilled analytical chemist, both techniques should be fine and of course colorless to color is easier to detect. One is less painful than the other. – M. Farooq Nov 1 '19 at 20:42