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Ch 2

Ch 2. Review of Scientific notation, significant digits, density, precision, and accuracy. Scientific Notation. Perform these calculations: (3.2 X 10 5 ) (6.02 X 10 23 ) = 1.9 X 10 29 (9.23 X 10 -8 ) / (6.1 X 10 23 ) = 1.5 X 10 -31 (7.9 X 10 -6 ) + (4.0 X 10 -8 ) = 7.94 X 10 -6.

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Ch 2

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  1. Ch 2 Review of Scientific notation, significant digits, density, precision, and accuracy

  2. Scientific Notation Perform these calculations: (3.2 X 105) (6.02 X 1023) = 1.9 X 1029 (9.23 X 10-8) / (6.1 X 1023) = 1.5 X 10-31 (7.9 X 10-6) + (4.0 X 10-8) = 7.94 X 10-6

  3. Starting from the Atlantic Side If you “run across” zeros before you cross a non-zero digit on the Atlantic side Those Zeros ARE Significant! 10.04000 0.00400

  4. Starting from the Pacific Side… 12.00300 Zeros on the pacific side Are NOT Significant 0.00456 0.0045600

  5. Atlantic: Are significant Pacific: Place holders 0.009 11.009 11.090 0.0090

  6. 45,000 4.1005 1,234,567,891 1,234,056,789 0.005 0.0050 1.0050 0.00304 10.00304 1 dozen eggs 1 mile 8 cats 1 000 m = 1 km 23.14 Significant Digits

  7. Round to the correct number of significant digits • 12.30 X 0.003 = • 12.30 X 0.0030 = • 12.30 X 0.00300 =

  8. Answers • 12.30 X 3 = 36.9, 40 • 12.30 X 3.0 = 36.9, 37 • 12.30 X 3.00 = 36.9

  9. Round to the correct number of significant digits • 120 / 3.14 = 5. 14 / 32.00= .4375 or .44 6. 200 X 0.500 = 100

  10. Answers 4. 120 X 3.14 = 380 5. 0.0120 X 0.7 = 0.008 6. 0.23 X 0.50600 =0.12

  11. Round to the correct number of significant digits 7.(6 X 104 ) (5.27 X 10-6 ) = 8. (6.809 X 104)/(9.200 X 10-6)

  12. Answers 7. (6 X 104 ) (5.27 X 10-6 ) = 0.3 or 3 x 10-1 8. (6.809 X 104)/(9.200 X 10-6) = 7.401 X 109

  13. Density • Density = mass volume Mass in grams Volume in ml or cm3 Units: g/ml or g/ cm3

  14. Precision and accuracy • Accuracy-how close a measured value is to an accepted value • Precision – how close a series of measurements are to 1 another. Show little variation over a series of trials.

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