Why is it necessary to rinse the clean burette before filling it with the unstandardised NaOH solution ?

Question

This is done during titration.

Answer 1

It's to ensure the burette is optimally clean so that you can yield the best titration results. The person who used it before you might not have cleaned it properly, for all you know - there might be some other dried solutions on the inside of the glassware. These aforementioned solutions could very well affect your titration process if, say, they're of an acidic nature (they'll neutralise the NaOH) or if they react with NaOH, which will result in your getting inaccurate results since a portion of NaOH would've reacted with said solutions instead of the acid you're titrating it with.

Also, it is also extremely dangerous if said chemicals left over inside the burette (no matter how clean it looks! Some solutions are colourless.) react violently with NaOH. One should always assume that all chemicals are dangerous in the laboratory, and you should always clean your apparatus properly (in the burette's case, rinsing) before using them.

Answer 2

Beacuse there may be contaminants in the burette, eg dust, or molecules left behind from when the tap water used to clean it evaporated.

It's just good practice really.

Answer 3

To remove any extraneous coatings on the inside of the burette.

Answer 4

so that d result is more accurate...the impurities inside the burette will affect the accurate of the experiment by changing its properties

Answer 5

So you don't contaminate the solution and effect your results