a 100ml graduated cylinder has a resolution of 1ml most of the times, so the error let's say is 0.5ml
a 100ml volumetric flask has a precision of 0.05ml, so for analytical work this is important.
which would be better, measure 100ml in 1ml increments with a syringe or just 100ml measured with a graduated cylinder?
error propagation theory, if the syringe as an error of +-0.05ml for example, you need to add all those errors together, so if you measure 100 times
1ml+-0.05ml at the end you would have 100ml+-5ml, but using a graduated cylinder with an error of 0.5ml you would have 100ml+-0.5ml
when i was doing lab for my quantitative analitical chemistry class i had to titrate with a burette (error of +-0.05ml) usually 200mg+-0.1mg of a
compound dissolved in 250ml using a volumetric flask, adding just 1 or 2 drops in excess during the titolation means an error of around 1% already, so
precision is a must. normally in an amateur lab this kind of precision is not necessary so a graduated cylinder is fine for 99% of things
[Edited on 11-10-2018 by Ubya] |