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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 Numbers-counted or defined-no uncertainty Measured Numbers-obtained with the use of some measuring device-always have some uncertainty 3 Measured Numbers 1 2 3 4 5 6 7 8 9 4 Measured Numbers square4 Precision-how close multiple measurements are to each other-directly related to the measuring device square4 Accuracy-how close a measurement is to the “true” or accepted value 2 2 5 Errors square4 Random Errors-due to uncontrolled variables-result in a decrease in precision square4 Systematic Errors-constant errors-lead to a decrease in accuracy, do not affect precision-can 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