CHEM 2121 Lecture 12: Lecture 1242014.pdf
Document Summary
We get result of 0. 01 g/oz . but can"t just based on that, need margin of error. Ex: reading absorbance scale: different people can see different measurements and even you might see something different if you do it multiple timesf. Not reproducible, equally likely to be + or -, cannot be eliminated (can be minimized) ex: neck of volumetric flask, want to fill it out exactly 100. 99. 96 ml as n --> infinity avg --> 100. 00 ml. When using flask, manufacturers can"t make measurements on it exact. 99. 74 ml as n -->infinity avg --> 99. 78 ml. Analyze a known sample; aka certified reference material; known b/c there"s error associated even w/ certified reference material -->your method should reproduce known value. Different people in other labs analyze same sample w/ same (or different) methods; analyses should agree w/in random error -->removes any systematic error associated w/ you as a researcher.
