Significant Figures, Precision, and Accuracy!
Jan 03, 2016
Significant Figures, Precision, and Accuracy!
Precision vs. 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
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
1.0 Answer: 2
60. Answer: 2
1.0 x 102 Answer: 2
• 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:Answer: 1
603 Answer: 3
6030 Answer: 3
60
Sig Fig Assignment:
• On a piece of notebook paper, copy the following numbers down, then indicate how many significant figures each number has:
a. 32 f. 310 002b. 32.0 g. 0.0048c. 45.1 h. 24.90d. 0.000045 i. 5.01e. 290 000 j. 34.00