This is one of those titration labs, maybe you could answer it?

Why must a buret be rinsed with NaOH solution before it is filled and not water?

Note: ( Buret will be full of NaOH )

2 answers

Distill water has pH = 7 and NaOH is a strong base (pH > 7)... if you mix NaOH with water, it will neutralize some of the base (decrease the pH to be closer to 7) and thus contaminate the NaOH solution.
If you rinse with water it dilutes the NaOH that you add later and that isn't what you want.