Experimental calculated values and Uncertainties

[Yoshimine]

1. After I calculated from my original data with lowest significant figure of 3, I got 0.3765 and uncertainty of 0.1274

2.original data with lowest significant figure of 2 .calculated value of 0.69897 and uncertainty of 0.0789

The Attempt at a Solution

This is how I answered
1. 0.377 uncertainty of 0.127
2. 0.70 uncertainty of 0.01

My teachers dosent mark our workbook so we don't know whether they are correct or not

any help is appreciated,thank you.

 

[tadchem]

I use the ASTM protocol for rounding (5's round to an even number: .15 rounds up while .25 rounds down). By that rule your 0.3765 rounds to 3 sig figs as 0.376, 0.1274 rounds to 3 sig figs as 0.127, 0.69897 rounds to 2 sig figs as 0.70, and 0.0789 rounds to 2 sig figs as 0.08.

 

[Yoshimine]

Can the uncertainty be 3 significant figure?

 

[JayneDoe]

To me, it would not make sense to report an uncertainty with more than one significant figure. Additionally, it wouldn't make sense to report something like '0.377 +/- 0.1' -- because your uncertainty is in the tenths place, the hundredth and thousandth places of the measurement are pretty worthless.

If you want a vaguely more authoritative reference, a quick google search will turn up http://www.wellesley.edu/Chemistry/Chem105manual/Appendices/uncertainty_sigfigs.html .

 

[Yoshimine]

I need to to be consistent with the original data and significant figur for uncertainty need to be 1 for my answer, but I cannot follow those two because it would not make sense.does it mean that there is no correct way to report?