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Scientific Measurements

Scientific Measurements. Unit 2 – For support see Chapter 2 in textbook. - Bechtum. Learning Targets. 1. I can use and convert correct SI units of measurement. 2. I can accurately use scientific notation and significant figures. 3. I can solve problems using dimensional analysis.

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Scientific Measurements

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  1. Scientific Measurements Unit 2 – For support see Chapter 2 in textbook. -Bechtum

  2. Learning Targets • 1. I can use and convert correct SI units of measurement. • 2. I can accurately use scientific notation and significant figures. • 3. I can solve problems using dimensional analysis. • 4. I can calculate density problems. • 5. I can distinguish between precision and accuracy.

  3. What is the difference? • Qualitative measurement – a measurement that gives descriptive nonnumerical results. (Qualities)‏ • Quantitative measurement – a measurement that gives definite, usually numerical results. (Quantities)‏

  4. Quantitative or Qualitative? 1 minute- turn to your partner! • The product was a white powder • 760 mL of Acetone was added to the flask • The test tube smelled like rotten eggs

  5. Scientific Notation Numbers are written as a coefficient and 10 raised to a power Examples: -1.63 x 103 8.7 x 10-5 2.045 x 1018

  6. Numbers Bigger Than 1: • Exponent is Positive • Positive Exponents move decimal to the right • Examples: Scientific Notation Standard Notation 438,904 376 8.348 x 106 3.402 x 103

  7. Numbers Smaller Than 1: • Exponent is Negative • Negative Exponents move decimal to the left • Examples: Scientific Notation Standard Notation 0.03054 0.0045834 3.02 x 10-5 7.6352 x 10-3

  8. Practice Time! • Utilize peers for feedback. • Ask questions!

  9. Significant Figures • -Note Packet- • Any number in a measurement that is certain or estimated (one past measuring device).

  10. Defining Significant Figures Group Activity (POGIL)! • Notes/ Piece of Paper • Writing Utensil • Complete as a GROUP! Make sure you feel comfortable with the ‘big’ ideas! • Assessment on big ideas at ______________

  11. Peer activity- Significant figures and measurement ALL GROUP Members participate in building understanding! Below are side jobs to learning and collaborating. • Getter 1 (1) • Group member that Collects and distributes materials for beginning of activity/day. • Getter 2 (2) • Group member that Collects and returns materials at the conclusion of activity/day. • Reporter (3) • Group member that shares thoughts with class; only member that can ask teacher question • Starter (4) • Group member that begins activities and keeps an eye on the time

  12. Proper Measurement • Estimate one digit past the smallest division on the measuring device. • Include the proper units. • Read instruments at eye level.

  13. What is the Length?

  14. What is the Volume?

  15. What is the temperature?

  16. What is the length?

  17. What is the volume?

  18. What is the Length?

  19. Define Significant Figures in your OWN words! • Share out definitions

  20. Analyzing Significant Figures • 650 m -2 Significant Figures • 4.083 km -4 Significant Figures • 42.0 s -3 Significant Figures • 7000 L -1 Significant Figure • 3.000 kg -4 Significant Figures • 0.008 mL -1 Significant Figure • 0.00560 cm -3 Significant Figures • 6050 mg -3 Significant Figures Your task is to device a set of “rules” for determine the number of significant figures in a value/number. (3 Minutes!) Be prepared to share out and explain your answers!

  21. Rules of Significant Figures • All non-zero numbers are significant. • Sandwiched zeros (those that occur between two significant figures) are significant. • Zeros that are only placeholders for a decimal are not significant. • Zeros at the end of a number that also contains a decimal are significant. • Exact numbers (no doubt or uncertainty in the value) may be thought of as having an infinite number of significant figures. These include numbers that were counted or are defined values (i.e., conversion factors)

  22. Determining the number of sig figsModel • 0.09 cm • 0.050 cm • 506 g • 801.0 g • 3073.00 cm3 • 0.0005 dm • 0.1020 cg • 10.001 ml

  23. Practice time 3 minutes! • Question 3

  24. Math Rules Using Sig Figs • Addition and Subtraction • answers should be rounded to the same number of decimal placesas the measurement with theleastnumber of decimal places • Multiplication and Division • round the answer to the same number ofsig figsas the measurement with theleast number of sig figs

  25. Math Using Sig Figs Model Solve the following and report out using the correct significant figures and units. • 1.35 m x 2.467 m = • 1035 m2 / 42 m = • 12.01ml + 35.2 ml + 6 ml = • 5546 g – 28.9 g = • 0.021 cm x 3.2 cm x 100.1 cm =

  26. Rounding • 5 or higher round up • 4 or less round down • Examples: 3 Significant Figures • 45.68 • 68.25 • 65.93 • 9.756

  27. Practice time 4 minutes! • Question 4, 5, and 6

  28. INTERNATIONAL SYSTEM OF UNITS • The International System of Units (SI) is the measurement system used by scientists. • Unit of Length =meter(m)‏ • Unit of Time = second (s) • Unit of Temperature = Kelvin (K) • Unit of Mass = kilogram (kg)‏ • Unit of Amount = mole(mol)

  29. Metric Conversions

  30. Practice Problems Questions 2 and 3!

  31. Mass and Weight • Mass • The amount of matter an object is composed of (grams, kg, pounds) • Weight • The amount of gravitational pull an object has (Newtons) • **A person that has a mass of 200 pounds, weighs 889N.

  32. Can a person be… • massless? • weightless?

  33. Check for Understanding • Describe the term accuracy in your own words. • Describe the term precision in your own words.

  34. UNCERTAINTY IN MEASUREMENTS • Accuracy describes how close a measurement comes to the true value. • Precision is how close a series of measurements are to one another.

  35. Uncertainty • Accurate, Precise, Neither, or Both?

  36. Uncertainty • Accurate, Precise, Neither, or Both?

  37. Uncertainty • Accurate, Precise, Neither, or Both?

  38. Uncertainty • Accurate, Precise, Neither, or Both?

  39. Four student’s lab results are posted below. Assuming that the density of water at the specified temperature of the day the lab was conducted was 1.00g/mL answer the following questions. • 1.) Which student has both the highest accuracy and highest precision in their data collected? • 2.) Which student has both the lowest accuracy and lowest precision in their data collected? • 3.) Which student has the highest precision, but low accuracy in their data collected? • 4.) Which student has high accuracy, but low precision in their data collected?

  40. Dimensional Analysis Purpose: To convert between units using the factor-label method.

  41. Conversion Factors

  42. Dimensional Analysis • 1. 261 g kg • 2. 3 days seconds • 3. 9,474 mm cm • 4. 0.73 kLL • 5. 5.93 cm3m3 • 6. 498.82 cg mg • 7. 1 ft3 m3 (Note: 3.28 ft = 1 m) • 8. 1 year minutes • 9. 175 lbs kg (Note: 2.2 lb = 1 kg) • 10. 4.65 km m • 11. 22.4 kg/L to kg/mL

  43. Your Turn! • Traveling at 65 miles/hour, how many feet can you travel in 22 minutes? (1 mile = 5280 feet)

  44. What is the same? What is different? Which is more dense? Why?

  45. Density • Density – the ratio of the mass of an object to its volume • Density = mass/volume • If a sample of aluminum has a mass of 13.5g and a volume of 5.0 cm3, what is its density? • 2.7 g/cm3

  46. Density vs. Mass • A large metal weight would be both dense and heavy.

  47. Density vs. Mass • A single balloon would be neither dense nor heavy.

  48. Density vs. Mass • A small metal weight would be dense, but not particularly heavy

  49. Density vs. Mass • Enough balloons will be heavy, but still aren't dense.

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