Hello, I'm conducting an extended essay in which glass gas syringes, accurate to (± 1.0 cm^3), are used. I have conducted two trials, and obtained volumes which each carry an uncertainty of (± 1.0 cm^3). My question is: When I average my results from two trials, does the uncertainty remain (± 1.0 cm^3), or does it become (± 2.0 cm^3)? Thanks very much for your help!

when you average a number of measurements, in general the error decreases, this is because your result becomes more accurate over many measurements (the fluctuations are minimised). Very roughly, for n measurements, the error is 1/root(n) of the error of one measurement.

so in the case of 2 measurements it would be ± 1/1.4 * 1.0 cm^3

hope this helps