1. Today’s Do Now 8/11/2014  1) Five different individuals measured the volume of a sample of sulfuric acid. Their data is in the table to the right: IndividualMeasurement 12.85 22.87 32.84 42.85 52.86

2. Today’s Do Now 8/11/2014  Write each of the following numbers in scientific notation: 2. 1,490,000,000 3. 0.00000832  Write the following number in standard notation. 4. 5.36 x 10 -2 1.49 x 10 9 8.32 x 10 -6 0.0536

3. Our first objective… By the middle of this class period, I will be able to… convert between units of measure using dimensional analysis.

4. Take a minute… Mark Cuban has decided that he wants to leave his position as general manager and open a bracelet shop. Before he leaves, he needs to confiscate 4 dozen bracelets from his players to start his shop. How many bracelets total is Mr. Cuban going to confiscate?

5. Dimensional Analysis  Dimensional Analysis: a problem solving method used to convert between units.  To change from one unit to another we will use a conversion factor. Unit 1 x conversion factor = Unit 2

6. When you solved the Cuban mystery you used a conversion factor 4 dozen bracelets x = 48 bracelets 12 bracelets 1 dozen This is a conversion factor !

7. Equivalence statement  Equivalence statement: two measurements with the exact same value  Example: 1 dozen = 12

8. Conversion factor  Conversion factor: ratio of the two parts of an equivalence statement  Example: 1 dozen = 12 2 Possible conversion factors: 12 OR 1 dozen 1 dozen 12

9. GaGa for Dimensional Analysis  Example problem: Lady GaGa’s hat for her meat dress is 10.5 inches long. What is the length in centimeters?

10. Step 1 and 2 1) Identify your given. Circle it in the problem and write it down. 2) Identify your unknown. Circle it in the problem and write it down. Example problem: Lady GaGa’s hat for her raw meat dress is 10.5 inches long. What is the length in centimeters?

11. Step 3 3) Find the equivalence statement(s) that relates the two units.  1 inch = 2.54 cm

12. 4) Choose the correct conversion factor based upon your given and unknown.  ( 1 inch/2.54 cm) OR (2.54cm/1 inch) Step 4

13. Step 5 5) Multiply your given by your conversion factor; cross off the units that cancel!

14. Step 6 6) Round your answer to the correct number of significant figures Way to go!!

15.  The lizard Mr. Pope found was 5.62 cm long. What was the length of the lizard in inches?

16. What are the steps? 1. Identify given and unknown 2. Find an equivalence statement to relate the two 3. The denominator’s units must match the given. 4. The numerator’s units must match the unknown.

17. Next objective: By the end of this class period, I will be able to… determine the number of significant figures in an integer to perform calculations reporting the correct number of significant figures.

18. UNCERTAINTY IN MEASUREMENT Because Nothing in chemistry is ever certain…

19. Measuring Volume in the Lab  Volume is measured from the bottom of the meniscus

20. Uncertainty in Measurement  Any measurement involves an estimate and thus is uncertain to some extent

21.  There are 6 graduated cylinders around the room. Go find at least 2 and take the measurement you think a scientist would take.  YOU HAVE 1 MINUTE. Let’s get up and move…

22. Were you correct? NumberVolume 1 2 3 4 5 6

23.  Certain numbers are all of the numbers that can be said for sure. They will be the same even if 5 different people made a measurement.  Uncertain numbers are any numbers that require an estimate. Certain vs. Uncertain Numbers

24. Rules for counting Significant Figures

25. 1. Nonzero numbers always count Ex: 1457 has 4 sig figs Rules for counting Significant Figures

26. 1. Nonzero numbers always count 2. Leading zeros never count Ex: 0.0025 has 2 sig figs Rules for counting Significant Figures

27. 15,677 5 sig figs

28. 0.0391 3 sig figs

29. 1. Nonzero numbers always count 2. Leading zeros never count 3. Captive zeros always count Ex: 1.008 has 4 sig figs Rules for counting Significant Figures

30. 506 3 sig figs

31. 0.06002 4 sig figs

32. 1. Nonzero numbers always count 2. Leading zeros never count 3. Captive zeros always count 4. Trailing zeros only count if the number contains a decimal point Ex: 100 has only 1 sig fig 100. has 3 sig figs Rules for counting Significant Figures

33. 0.4700 4 sig figs

34. 2.40 x 10 3 3 sig figs

35. 5,000 1 sig figs

36. 1. Nonzero numbers always count 2. Leading zeros never count 3. Captive zeros always count 4. Trailing zeros only count if the number contains a decimal point 5. Exact numbers (have an unlimited number) Rules for counting Significant Figures

37.  Numbers that are determined by counting:  10 experiments  8 molecules  Definitions  1 inch = 2.54 cm What is an exact number??

38. Significant Figures and Rounding  If the digit to be removed:  A. is less than 5, the preceding digit stays the same (1.33  1.3)  B. is equal to or greater than 5, the preceding digit is increased by 1 (1.36  1.4)

39. 0.02345 Round to 3 significant figures! 0.023 5

40. 5012 Round to 3 significant figures! 5010

41. 0.07415 Round to 3 significant figures! 0.074 2

42. 10,001 Round to 3 significant figures! 1.00 x 10 4

43. 567.8 Round to 3 significant figures! 568

44.  Use your number cards to decide how many significant figures each number has Bonus Practice!

45. 1,000.1 5 sig figs

46. 0.004050 4 sig figs

47. 0.000405 3 sig figs

48. Last Step … back to your notes

49.  For multiplication & division  The limiting term is the one with the smallest number of significant figures Significant Figures in Calculations 4.56 x 1.4 = Round to 6.4 3 sig figs 2 sig figs 6.384

50.  Multiplication & Division  Smallest number of significant figures Significant Figures in Calculations

51.  Work out the following 4 problems with your lab partner on the back of your notes sheet: 1. 2.45 x 3.5 2. 8.315 ÷ 298 3. 135 x 246 x 0.000556 x 0.0998 x 155 4. (3.60 x 10 -3 ) x (8.123) ÷ 4.3 Work it Out! Swivel Style 8.6 0.027 9 286 0.0068

52.  For addition & subtraction  The limiting term is the one with the smallest number of decimal places 12.161 + 3.12 = Significant Figures in Calculations Round to 15.28 3 decimal places 2 decimal places 15.281

53.  Addition & Subtraction  Smallest number of decimal places Significant Figures in Calculations

54.  Work out the following 4 problems with your lab partner on the back of your notes sheet: 1. 12.11 + 18.0 + 1.013 = 2. 29.63 + 24.798 + 1.263 = 3. 1081 – 7.25 = 4. 8.445 x 10 5 – 9.44 x 10 2 = Work it Out! Swivel Style 31.1 55.69 1074 8.44 x 10 5