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Unformatted text preview: 1 1 1 Lecture 2 square4 Quantitative Measure of Matter (Chapter 2) square4 Precision and Accuracy square4 Errors square4 Significant Firgures square4 Units and Calculations (Chapter 3) 2 Quantitative Measure of Matter (chapter 2) square4 Numbers: Exact Numberscounted or definedno uncertainty Measured Numbersobtained with the use of some measuring devicealways have some uncertainty 3 Measured Numbers 1 2 3 4 5 6 7 8 9 4 Measured Numbers square4 Precisionhow close multiple measurements are to each otherdirectly related to the measuring device square4 Accuracyhow close a measurement is to the “true” or accepted value 2 2 5 Errors square4 Random Errorsdue to uncontrolled variablesresult in a decrease in precision square4 Systematic Errorsconstant errorslead to a decrease in accuracy, do not affect precisioncan be accounted for by calibration Any measurement has some uncertainty 6 Precision and Significant Figures square4 significant figures:all digits that are known with certainty plus one digit that is unknown (uncertain) square4 precision in a measurement is indicated by the number of significant figures 2.64 is more precise than 2.6 7 Measured Numbers 1 2 3 4 5 6 7 8 9 8 square4 Uncertainty in a series of measurements:...
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This note was uploaded on 03/10/2011 for the course CHEM 100 taught by Professor L during the Spring '11 term at Simon Fraser.
 Spring '11
 L

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