[spirochete]

A Class A 50 mL buret is said to have a tolerance of ±0.05 mL. Yet it is typically said that a Class A 50 mL buret can be read to ±0.01 mL.

How can both of these things be true at the same time?

[Arkcon]

I would assume because "tolerance" and "what it can be read to" each have a definition that is likely similar to, but not the same as, each other.  And very possibly neither is a synonym for "accuracy."  What can you pull together from textbook definitions for each term?

[Borek]

It is not different from having a voltmeter that shows 3 digits, but is known to have accuracy ±5%. Just because it displays something, doesn't mean it is right, right?

[curiouscat]

I'm still confused how he can read it to 0.01 ml.

That'd mean every ml range was sub-divided 100 times. That'd need 5000 marks on the 50 ml burette.

Something doesn't make sense.

[spirochete]

Unfortunately I can't look up "can be read to" in a glossary.  As for tolerance, it's defined as "manufacturer's stated uncertainty in the accuracy of a device. . ."

So tolerance is clearly an uncertainty in accuracy.  I believe that reading a buret to ±whatever is an indication of the precision to which it can be read.  So probably this is just a classic case of accuracy vs. precision that they teach you about in the first ten minutes of gen chem. I feel silly now. Thank you for your helpful comments.

[Arkcon]

Don't feel bad.  I'm always pointing the precision/accuracy dichotomy out, and then I went and screwed it up myself this morning.  http://www.chemicalforums.com/index.php?topic=68895.msg248209#msg248209