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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 Review of Scientific notation, significant digits, density, precision, and accuracy
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
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
Starting from the Pacific Side… 12.00300 Zeros on the pacific side Are NOT Significant 0.00456 0.0045600
Atlantic: Are significant Pacific: Place holders 0.009 11.009 11.090 0.0090
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
Round to the correct number of significant digits • 12.30 X 0.003 = • 12.30 X 0.0030 = • 12.30 X 0.00300 =
Answers • 12.30 X 3 = 36.9, 40 • 12.30 X 3.0 = 36.9, 37 • 12.30 X 3.00 = 36.9
Round to the correct number of significant digits • 120 / 3.14 = 5. 14 / 32.00= .4375 or .44 6. 200 X 0.500 = 100
Answers 4. 120 X 3.14 = 380 5. 0.0120 X 0.7 = 0.008 6. 0.23 X 0.50600 =0.12
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)
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
Density • Density = mass volume Mass in grams Volume in ml or cm3 Units: g/ml or g/ cm3
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.