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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: Ter on December 19, 2012, 12:02:23 AM

Title: Burettes
Post by: Ter on December 19, 2012, 12:02:23 AM

" A burette is used when the volume is unknown. "
From IB Chemistry HL

Can you explain what this means please? Isn't the volume from the burette known, by looking at the markings on the burette? Where is the unknown portion?

Thank you very much

Title: Re: Burettes
Post by: ATMyller on December 19, 2012, 02:16:27 AM

More like "A burette is used to determine the unknown volume.". This of course requiers a method to observe the equilvalent point (pH-meter, conductometer, indicator etc.).

But yes if you don't known how much you need to add, the burette is a good choice to administer the compound in a controlled fashion.

Title: Re: Burettes
Post by: fledarmus on December 19, 2012, 10:10:07 AM

Good answer ATMyller...

If you know from the beginning exactly how much volume you need to add, it is more convenient to add it by a pre-measured method, like a syringe, graduated cylinder, or graduated pipette. If you don't know exactly how much volume you will need to add, but after you have added it you will need to know exactly how much you added, a burette is the way to go. It allows you to add the solution in a carefully controlled, dropwise manner, then get an accurate determination of how much solution was added when the addition is complete.