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Chapter 3

Chapter 3. Scientific Measurement. Ch 3.1 The Importance of Measurement. Ch 3.1 The Importance of Measurement. Qualitative Measurement – measurement that gives descriptive nonnumeric results Example: Feel some ones head to see if they are running a fever or not

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Chapter 3

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  1. Chapter 3 Scientific Measurement

  2. Ch 3.1 The Importance of Measurement

  3. Ch 3.1 The Importance of Measurement • Qualitative Measurement – measurement that gives descriptive nonnumeric results • Example: Feel some ones head to see if they are running a fever or not • Quantitative Measurement – measurement that gives definite usually numeric results • Example: Measure some ones temperature with a thermometer

  4. Scientific Notation • Used to write small or large numbers • N x 10n • N = a number between 1 and 10 • n = a positive or negative integer

  5. Scientific Notation • Mass of an atom of gold • 0.000000000000000000000327g • 3.27 x 10-22g • Number of hydrogen atoms in 1g • 602000000000000000000000 • 6.02 x 1023 atoms

  6. Coefficient Scientific notation has three parts to it: the coefficient, base, and exponent

  7. Scientific Notation: Multiply and Divide • Multiply coefficients and add exponents • (3.0 x 104) x (2.0 x 102) = 6.0 x 106 • Divide coefficients and subtract exponents • (3.0 x 104) / (2.0 x 102) = 1.5 x 102

  8. Scientific Notation: Addition and Subtraction • Make the exponents the same, then add or subtract • 3.0 x 104 + 2.0 x 102 = • 300.0 x 102 + 2.0 x 102 = 302.0 x 102

  9. Chapter 3.2 Uncertainity

  10. Accuracy and Precision • Accuracy – how close a measurement is to the true value of the quantity measured • Precision – how closely two or more measurements of the same quantity agree with one another

  11. Accuracy and Precision • A student was asked to measure the length of the hallway. He came up with the following lengths. • 10.2m, 10.1m, 10.2m • The actual length was 12.5m. • How would you describe his results?

  12. Accuracy and Precision • A student was asked to determine the mass of a beaker. She came up with 34.8g, 34.7g and 34.7g. • The actual mass was 34.8g. • How would you describe her results?

  13. Percent Error • % Error = accepted value – experimental value x 100 accepted value The correct answer Your answer The correct answer

  14. Percent Error • A student was asked to determine the mass of a beaker. She came up with an average mass of and 34.7g. • The actual mass was 34.8g. • What is the percent error? • 34.8 g –34.7 g x 100 = 0.287 % Error 34.8

  15. Significant Figures Abbreviation: sig fig Why are sig figs so IMPORTANT?

  16. Significant Figures 1) Any digit that is not zero is significant • 24.7 meters 3 sig figs • 0.743 meters 3 sig figs • 74 grams 2 sig figs

  17. Significant Figures 2) Zeros between nonzero digits are significant • 7003 mL 4 sig figs • 40.7 cm 3 sig figs • 1.5035 g 5 sig figs

  18. Significant Figures 3) Zeros to the left of the first nonzero digits are not significant • 0.0071 km 2 sig figs • 0.420 g 3 sig figs • 0.00009999 L 4 sig figs

  19. Significant Figures 4) If a number is greater that 1, then all the zeros written to the right of the decimal point count as significant • 43.00 m 4 sig figs • 1.0100 mg 5 sig figs • 9.00 cL 3 sig figs

  20. Significant Figures 5) Numbers without a decimal, the trailing zeros may or may not be significant. It will depend on other information in the problem. • 5,000 1 or 4 sig figs • 68,900 3 or 5 sig figs • 52,010,000 4 or 8 sig figs

  21. Significant Figures 6) Unlimited significant figures when: - Counting an exact number (whole number only) such as number of people in the class - Exactly defined quantities 60 minutes = 1 hour

  22. Significant Figures for Calculations • Addition and Subtraction: The answer can not have more digits to the right of the decimal point than either original number. (Least number of decimal places) • 400.567 + 21.0 = 421.567 421.6 • 68.892 – 48.47 = 20.422 20.42

  23. Significant Figures for Calculations • Multiplication and Division: The number of significant figures in the final product or quotient is determined by the original number with the smallest number of significant figures. • 12,003 x 45 = 1,525÷ 30.1 = 540,135 50.66445183 540,000 50.7

  24. Chapter 3.3 SI Units • International System of Units • From the French: Le Systeme International d’Unites

  25. SI Units

  26. SI Units (continued)

  27. Prefixes with SI Units

  28. How to remember the basic metric prefixes? Mnemonics :These stand for the Metric prefixes and base unit. kilo hectodeca base decicentimilli • Kittens Hate Dogs Because Dogs Cant Meow • Kangaroos Hop Down My Driveway Christmas Morning • Kings Hate Dragons Because Dragons Can’t Make Money • King Henry Died Bloated Drinking Chocolate Milk • Kangaroos Hop Down Mountains Drinking Chocolate Milk

  29. giga mega kilo hectodeca BASE decicentimilli micro nanopico • King Henry Danced MerrilyDown Center Main Meeting Nice People • Great Mighty King Henry Died By Drinking Chunky Milk • Good Models Know How Dunkin Donuts Can Make U Not Petit

  30. Chapter 3.4 Density • Density = Mass / Volume • d = m/v • 1 g/cm3 = 1 g/ml • 1 mL = 1 cm3

  31. Density Column

  32. Chapter 3.5 Temperature Scales • 0C = K – 273 • K = 0C + 273 • Freezing • 00C = 273K • Boiling • 1000C = 373K • Absolute Zero • O K

  33. Temperature Scales

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