[Emma]

Hello,

im taking the course intro to analytical chemistry and Im still confused about the concept of uncertainity

I understand that getting the Standard deviation of the mean is sufficient enough

However, my prof. told me that if my SD is LOWER than the uncertainity provided by the manufacturers of the instrument, i must use whichever HIGHER.

My issue is, how can I estimate the exact number of uncertainity ? e.g. provided uncertainty for Spectrometer (Thermo Spectronic 200) ± 0.01 at 0.3 AU ( AU is Absolute Uncertainty).

But what if I get an average reading of , say 0.87 for my absorbance, what will be my uncertainity value according to the manufacturer accuracy ? my calculated SD is smaller than  ± 0.01.

[onespeedgo]

If I understand things properly, your prof said to use the higher uncertainty (st.dev) if your calculated is lower than the manufacturers. You said that yours is lower, so it seems like the correct thing to do in this case is to state your value as 0.87 +/-0.01.

Also, I'm pretty sure that AU is is the general term for absorbance units.