Lecture3-C - All measurements have some uncertainty...

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1 All measurements have some uncertainty: Instruments are not perfect Individuals make mistakes Methods and/or techniques have limitations Scientific measurements are reported with all the exactly known numbers and the estimated one: 15 7; 841 9; 0.000552 1 In the sciences, accuracy and precision have different meanings. A Precision - is related to the reproducibility of the measurement - number of digits to be reported on a measured value. 155.9 4 , 155.9 3 , 155.9 5 , 155.2 2 , reproducible 155 . 8 7 , 155 . 9 7 , 155 . 6 1 , 155 . 1 1 , not reproducible Accuracy - indicates how closely the measured value agrees with some known value . Significant figures/digits - used for determining uncertainty of a measurement Significant figures / digits - all the definitely known numbers and the doubtful number Uncertainty (margin of erro ) a range of values likely The last digit written in a measurement is considered to be estimated (doubtful). 541.1
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This note was uploaded on 01/14/2012 for the course CHEM 1215 taught by Professor Staff during the Fall '08 term at Oklahoma State.

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Lecture3-C - All measurements have some uncertainty...

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