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Course Outline

Course Outline. Math Review. Measurement Using Measurements. Accuracy:. How close a measurement is to the actual size of the object. Precision:. How close a series of measurements are to each other . ACCURATE = CORRECT PRECISE = CONSISTENT. Accuracy vs Precision.

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Course Outline

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  1. Course Outline

  2. Math Review

  3. Measurement Using Measurements

  4. Accuracy: How close a measurement is to the actual size of the object. Precision: How close a series of measurements are to each other. ACCURATE = CORRECT PRECISE = CONSISTENT Accuracy vs Precision

  5. Significant Figures Indicate precision of a measurement. Recording Sig Figs: Sig figs in a measurement include the known digits plus a final estimated digit. Your answer you record can only ever be as accurate as the question. 2.35 cm

  6. Significant Figures Counting Sig Figs (See Handout) As a general rule, your answer should have the same number of sig figs as the number in the question with the lease sig figs. Count all numbers EXCEPT: Leading Zeroes--0.0025 2 Sig Figs

  7. Significant Figures Counting Sig Figs Examples Practice 1. 23.50 4 Sig Figs 402 2. 3 Sig Figs 3. 5,280 4 Sig Figs 4. 0.080 2 Sig Figs

  8. Significant Figures Calculating With Sig Figs Multiply/Divide The # with the fewest sig figs determines the # of sig figs in the answer (13.91 g/cm3) (23.3 cm3) 324.103g = 4 Sig Figs 3 Sig Figs 3 Sig Figs 324 g

  9. Significant Figures Calculating With Sig Figs (continued) Add/Subtract The # with the lowest decimal value determines the place of the last sig figs in the answer. 3.75 mL + 4.1 mL 7.9 mL 7.85 mL

  10. Significant Figures Calculating With Sig Figs (continued) Exact Numbers The exact numbers do not limit the # of sig figs in the final answer. Example: 12 Students in a class. 1 Meter. 12.0000000000 1.0000000000

  11. Significant Figures Practice Problems 1. (15.30 g) ÷ (6.4 mL) = 2.390625 g/mL 2 S.F 2 S.F 4 S.F ~ 2.4 g/mL 2. 18.9 g - 0.84 g 18.1 g 18.06 g

  12. Scientific Notation 65,000 kg  6.5 X104 kg Converting into Scientific Notation: You take the number and move the decimal however many spots it takes until you have #.####### 1 # in front of decimal, and the rest behind. However number of spots you moved the decimal becomes the X 10something General Rule: Large # (>>>1) Positive exponent on 101 or bigger Small # (<<<1) Negative exponent on 10-1 or smaller

  13. Scientific Notation Examples: 6,300,400 km = 6.3 X106 km 3 2 1 4 6 5 0 0 8.5 X 10-7 L = 85 L 0 0 0 0 0 1 7 6 4 5 3 2

  14. Scientific Notation Practice Problems: 1. 2,400,000 μg 2.4 X 106μg 2. 0.00256 kg 2.56 X 10-3 kg 3. 7 X 10-5 km 0.00007 km 4. 6.2 X 104 mm 62,000 mm

  15. Scientific Notation Calculating with Sci. Notation (95.44 X 107 g) ÷ (8.1 X 104 mol) Type on your calculator: 4) ^ (5.44 X 10 ^ 7) (8.1 X 10 ÷ = 671.6049383 ~ 6.7 X 102 g mol

  16. We can only add and subtract numbers with the same units. • However, when we divide the units are divided • And when we multiply the units are multiplied. • Ex: 100km / 1 hour = 100km/hr • ex: 5.0m * 2.0m = 10m2 Notice

  17. MeasurementUnit Conversions

  18. Find the difference between the exponents of the two prefixes. • 2. Move the decimal that many places. SI Prefix Conversions

  19. Prefix Symbol Factor M 106 mega kilo BASE UNIT deci- centi- milli- micro- nano- pico- k 103 --- 100 d 10-1 c 10-2 m 10-3 μ 10-6 n 10-9 SI Prefix Conversions p 10-12 Move decimal to the left. Move decimal to the right.

  20. 20cm = ___________meters 0.032 L = _____________mL 45μm = ______________nm 805 dm = _____________km 0.2 32 45000 0.0805 Practice Problems

  21. The “Factor-Label Method Units or Labels are canceled out After you cancel out all the “repeated” units, you are left with the units you use in your answer. Dimensional Analysis

  22. The “Factor-Label Method Units or Labels are canceled out After you cancel out all the “repeated” units, you are left with the units you use in your answer. Dimensional Analysis

  23. 1cm3 X 4 g = 4 g 1cm3 Dimensional Analysis

  24. X X 4 g = 4 g • 1cm3 1cm3 Cross Multiply and Divide 4 X 1 = 4 ÷ 1 = 4

  25. Identify starting & ending units. • Line up conversion factors so units cancel. • Multiply all top numbers & divide by each bottom number. Cross multiply and divide • Check units & answer

  26. How many milliliters are in 0.946 Liters of milk? Practice Problems

  27. How many milliliters are in 0.946 Liters of milk? 10-3 = 1000 so….. 1000 ml/1L Practice Problems

  28. How many milliliters are in 0.946 Liters of milk? 0.946L x 1000ml/L = Use your calculator or just move the decimal 3 spots to the right. 946ml 3 Sig Figs ~ 946ml Practice Problems

  29. A roll of wire is 1.3 M long. How many 1.5 cm long pieces can you cut from the roll? Well first we need the same units. So convert both to centimeters or both to meters. Practice Problems

  30. A roll of wire is 1.3 M long. How many 1.5 cm long pieces can you cut from the roll? Practice Problems

  31. A roll of wire is 1.3 M long. How many 1.5 cm long pieces can you cut from the roll? 102 = 100 So…. 1m = 100cm Practice Problems

  32. A roll of wire is 1.3 M long. How many whole 1.5 cm long pieces can you cut from the roll? 1.3m X 100cm/m =130cm. 130 cm ÷ 1.5 cm/ piece = 86.666666666667 pieces ~ 86 pieces Practice Problems

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