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Significant Figures, Precision, and Accuracy!. Accuracy - Refers to how closely a measured value agrees with the correct value. Precision -Refers to how closely individual measurements agree with each other. Precision vs. Accuracy.
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Accuracy -Refers to how closely a measured value agrees with the correct value Precision -Refers to how closely individual measurements agree with each other Precision vs. Accuracy
Describe the following in terms of precision and/or accuracy… • Scenario #1: A chemistry student uses a graduated cylinder to measure the volume of a liquid and found the measurement to be 20.1 mL. The actual measurement was 27.3 mL. • Scenario #2: A man practices his dart throws in attempt to hit the bulls-eye! Here are his results:
Determining the number of sig. figs. in a number • Picture a map of the U.S…. • If a decimal point is present in a number, count from the Pacific side. • Start counting with the first nonzero digit. • All digits from here to the end, including zeros, are significant.
Examples: • 0.00682 Answer: 3 Answer: 2 • 1.0 Answer: 2 • 60. Answer: 2 • 1.0 x 102
If the decimal point is absent, start counting from the Atlantic side. • Start with the first nonzero digit. • All digits from here to the end, including zeros, are significant.
Examples: • 60 Answer: 1 Answer: 3 • 603 Answer: 3 • 6030
Sig Fig Assignment: • On a piece of notebook paper, copy the following numbers down, then indicate how many significant figures each number has: • 32 f. 310 002 • 32.0 g. 0.0048 • 45.1 h. 24.90 • 0.000045 i. 5.01 • 290 000 j. 34.00