2. Course Outline

3. Math Review

4. Measurement Using Measurements

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

6. 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

7. 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

8. Significant Figures Counting Sig Figs Examples Practice 23.50 1. 4 Sig Figs 2.402 3 Sig Figs 3. 5,280 4 Sig Figs 4. 0.080 2 Sig Figs

9. 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/cm 3 ) 4 Sig Figs (23.3 cm 3 ) 3 Sig Figs = 324.103g 3 Sig Figs 324 g

10. 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 7.85 mL 7.9 mL

11. 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

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

13. Scientific Notation 65,000 kg  6.5 X10 4 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 10 something General Rule: Large # (>>>1) Positive exponent on 10 1 or bigger Small # (<<<1) Negative exponent on 10 -1 or smaller

14. Scientific Notation 6,300,400 km Examples: 123 4 56 = 6.3 X10 6 km 8.5 X 10 -7 L= 85 L 1 00 23 4 5 67 00000

15. Scientific Notation Practice Problems: 1. 2,400,000 μg 2. 3. 4. 0.00256 kg 7 X 10 -5 km 6.2 X 10 4 mm 2.4 X 10 6 μg 2.56 X 10 -3 kg 0.00007 km 62,000 mm

16. Scientific Notation Calculating with Sci. Notation (95.44 X 10 7 g) ÷ (8.1 X 10 4 mol) Type on your calculator: (5.44 X 10 ^ 7) ÷ (8.1 X 10 ^ 4) = 671.6049383 ~ 6.7 X 10 2 g mol

17. Notice 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 = 10m 2

18. Measurement Unit Conversions

19. SI Prefix Conversions 1.Find the difference between the exponents of the two prefixes. 2. Move the decimal that many places.

20. SI Prefix Conversions Prefix Symbol Factor mega kilo BASE UNIT deci- centi- milli- micro- nano- pico- M k d c m μ n p --- 10 6 10 3 10 0 10 -1 10 -2 10 -3 10 -6 10 -9 10 -12 Move decimal to the left. Move decimal to the right.

21. Practice Problems 1)20cm = ___________meters 2)0.032 L = _____________mL 1)45 μm = ______________nm 1)805 dm = _____________km 32 0.2 45000 0.0805

22. Dimensional Analysis 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.

23. Dimensional Analysis 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.

24. Dimensional Analysis 1cm 3 X 4 g = 1cm 3 4 g

25. Cross Multiply and Divide X X 4 g = 1cm 3 4 g 4 X 1 = 4 ÷ 1 = 4

26.  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

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

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

29. Practice Problems 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

30. Practice Problems 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.

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

32. Practice Problems A roll of wire is 1.3 M long. How many 1.5 cm long pieces can you cut from the roll? 10 2 = 100 So…. 1m = 100cm

33. Practice Problems 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