using a burette (1 Viewer)

[idling fire]

For some reason, I have the greatest difficulty in using a burette.

I can rinse with the appropriate solution and fill it accurately, I just can't turn it on/off.

The 'rough' run through goes ok, because accuracy isn't the concern, but for real titrations, I'm useless! My results are always so varied, just because I stuff up when trying to stop the burette. I try going drop by drop, then try to stop between drops close to the end point, but I either can't stop the burette in time, or turn it on more, or something stupid of that nature. I'm also pretty freaked about running out of time in the prac exam... especially with the amount of stuff ups I make with these burettes...


Any tips on using them would be great...

 

[Miss-K-Lee-2007]

How to be accurate in tirations:

• make sure that ALL glassware has been washed thoroughly with distilled water and whatever you will be putting in it at least 3 times each eg- burette: distilled water x 3 then acid rinse x 3
• when reading measurements make sure its at eye level
• read the measurements from the bottom of the miniscus
• when dispersing the solution from the burette into the conical flask do so SLOWLY!
• once the end point is just about to be reached add the titrant dropwise otherwise you will go past the end point.
• when using phenalphalein the end point is reached when it is the lightest pink you can get.
• Remember practise is the key!

if your really having that much trouble talk to your teacher and ask if you can practise titrations at lunch times or talk to him/her about entering the titration comp (They will know all about it) for extra practise.

 

[airie]

Heh, I use my left hand to shake the flask while using my right hand to control the tap, and sometimes while I go drop by drop near the end point, I stop every two or three drops and wait for the colour to settle. But then that could take a long time

 

[krayzie_]

Yes when you got the end point of your first titrant then you know it should be around there so once you get near the end point slow down by a few drops like airie say stop the burrette and shake it so it all settles then dropwise again entil u see your colour change!

 

[Forbidden.]

Heh, I use my left hand to shake the flask while using my right hand to control the tap, and sometimes while I go drop by drop near the end point, I stop every two or three drops and wait for the colour to settle. But then that could take a long time

Heh, I use my right hand to shake the flask while using my left hand to control the tap, and sometimes while I go drop by drop near the end point I swirl the flask regularly to evenly distribute the titre, I stop every two or three drops and then I swirl the flask again to evenly distribute the titre and wait for the colour to settle . But then that could take a long time but then it's more accurate

Hi and thnx.

 

[Miss-K-Lee-2007]

shake it so it all settles quote]

NO! you never shake it.. you continuously gently swirl the flask. And when I get near the end point add it dropwise stopping after 1-2 drops and gently swirling the flask.. Dont worry about running out of time they will give you plenty of time to do it...and dont rush.. its seems like u are quite impatient and dont go slowly enough..

 

[idling fire]

Lol, I'm not impatient. My hand just slips... or I forget which way is 'off'.

Anyway, thanks guys. I'll see how I go next time.

 

[xiao1985]

practice makes perfect...

also, try tune the radio some times, it help i think... (the act of turning the knob slowly)

and sometimes, when it's half open, it takes awhile (2-3 secs) before a drop will come out.... be patient...