# CHEM 1201 Lecture : Chem 1201 Notes Jan 19

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15 Mar 2019
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## Document Summary

Different measuring devices have different uses and different degrees of accuracy. Accuracy refers to the proximity of a measurement to the true value of a quantity. Precision refers to the proximity of several measurements to each other. Significant figures refers to the digits that were measured. All measurements have some degree of uncertainty or error associated with them. 3. 5678 ml has five significant figures: all nonzero digits are significant, zeroes between two significant figures are themselves significant. 5. 007 m (four significant figures: zeroes at the beginning of a number are never significant. 0. 0003 ml = 3 x 10-4 ml (one significant figure: zeroes at the end of a number are significant if a decimal point is written in the number. 0. 03500 g = 3. 500 x 10-2 g (four significant figures: zeroes at the end of a number before a decimal point are ambiguous. Round up if the first (of several) non-significant figures is >5.