1. Active Chemistry Chapter 1 Activity 3
Accuracy, Precision, and Significant Figures

2. I. Accuracy, Precision, & Error
A. Accuracy – how close a measurement comes to the “true value”. 1. Ex: Throwing Darts true value = bull's-eye

3. B. Precision – how close a series of measurements are together. 1
B. Precision – how close a series of measurements are together. 1. Ex: Throwing Darts

4. C. Explanation Poor Accuracy Poor Precision Poor Accuracy
Good Precision
Good Precision
Good Accuracy

5. II. Significant Figures
A. Def – all digits known plus one estimated one. 1. Measurements must be recorded with significant figures. 2. Water Drop Example…

6. 2. Guidelines for Sig Fig’s a
2. Guidelines for Sig Fig’s a. Zeros are significant if… the zero is between non-zero digits 409 (3 sig figs) the zero is after non-zero digits and not being used to locate the decimal point (3 sig figs) b. Zeroes are not significant if… the zero follows non-zero digits and is being used to locate the decimal point or for clarity. 640 (2 sig figs) (2 sig figs) (5 sig figs) c. All measured nonzero digits are significant

7. 3. Rounding with Sig Figs -Express the following #’s to 3 sig figs  = 422,000  =  1 = 1.00  8222 = 8,220  0.42 = .420

8. 4. Scientific Notation + Sig figs A
4. Scientific Notation + Sig figs A. All #’s in scientific notation are counted as significant figures. B. Ex: x 103 = 5 sig figs 2.77 x 106 = 3 sig figs

9. 5. Adding and subtracting A
5. Adding and subtracting A. The answer must not contain any sig figs beyond the place value common to all #’s B. Ex: (not 6.815)

10. 6. Multiplication and Division A
6. Multiplication and Division A. The answer must not contain more sig figs than the least # of sig figs. B. Ex: 3.1 x (not )

11. In Class Problems
1. How many sig figs? -123 meters meters -40,506 kg x 103 kg and x and 10.7 / x x 104