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Take out a blank piece of paper or Quiz

Take out a blank piece of paper or Quiz. 1/3 sheet Quiz 1.3. Density Luster Ductility Flammability. ________ is a chemical property. Groups on the Periodic Table are.. . Horizontal Small Vertical Blue. Measurements and Calculations Notes Ch 2.2. Open your book to page 33.

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Take out a blank piece of paper or Quiz

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  1. Take out a blank piece of paper or Quiz

  2. 1/3 sheet Quiz 1.3 • Density • Luster • Ductility • Flammability ________ is a chemical property. Groups on the Periodic Table are.. • Horizontal • Small • Vertical • Blue

  3. Measurements and CalculationsNotes Ch 2.2 Open your book to page 33

  4. Measurements and CalculationsNotes Ch 2.2 Open your book to page 33

  5. SI Base Units The quantity symbol appears in the equation while the unit symbol appears in the answer!

  6. SI Derived Units 1m3=1,000,000 cm3 & 1 cm3=1mL

  7. SI Prefixes There are some that are missing! You must still account for them!

  8. Progress Check Can you… • Distinguish between a quantity and a unit? • Name the SI units for length, mass, time, volume, and temperature?

  9. Please, consider the following: If today is Sunday, what is the day that follows the day that comes after the day that precedes the day before yesterday? Why would it be reasonable to say that the greatest gift modern society had received from the Arabs was nothing? 53,55

  10. Density • The ratio of mass to volume or the amount of mass in a given amount of material • SI unit: kg/m3 • Usable unit: g/mL or g/cm3 • Varies with temperature 1ml=1cm3

  11. Density • Water has a density of 1g/mL • D<1 will float in water • D>1 will sink in water If the egg didn’t change density, what must have happened?

  12. Density = mass/volume • D=m/V • What is the density of an object with a mass of 250 g and a volume of 10.0 mL?

  13. Great foolproof ways to solve science problems… • State what you know. • State what you want to know. • Find an equation that contains those variables. • Solve the equation for what you want to know. • Plug and chug!

  14. What is the density of an object with a mass of 250g and a volume of 10.0 mL? • State what you know. • m = 250 g • V = 10.0 mL • State what you want to know. • D = ?

  15. What is the density of an object with a mass of 250g and a volume of 10.0 mL? 3. Find an equation that contains those variables. D=m/V 4. Solve the equation for what you want to know. D=m/V • m = 250g V = 10.0 mL D = ?

  16. What is the density of an object with a mass of 250g and a volume of 10.0 mL? • D= 250g/10.0 mL = 25 g/mL Will this object float or sink in water? • m = 250g V = 10.0 mL D = ? D=m/V

  17. Progress Check Can you… • Solve for density, volume or mass given the other two? • Convert from one unit to another?

  18. ½ sheet Quiz 2.1June 5th • Pound • Slug • Liter • Gram ________ is the SI unit for mass. _______ is not a unit of density. • Kg/m3 • cm3 • g/cm3 • g/ml

  19. Open your Packet • Density Practice page 5

  20. Calculate the density of a material that has a mass of 52.457 g and a volume of 13.5 cm3.

  21. How many cm3 would a 55.932 g sample of copper occupy if it has a density of 8.92 g/cm3?

  22. What is the mass of a 350 cm3 sample of pure silicon with a density of 2.336 g/cm3?

  23. If 30.943 g of liquid occupy a space of 35.0 mL, what is the density of the liquid in g/cm3?

  24. Pure gold has a density of 19.32 g/cm3. How large would a piece of gold be if it had a mass of 318.97 g?

  25. Classwork is… • Finish Density Practice page 5 • Pg 40 (1-3) and 42 (1-2) (Practice) • Read CH 2.3 Keep your packets, turn in your Questions ½ sheet in 1 minute

  26. Say it with me… • No Units No Points!

  27. ½ sheet Quiz 2.2 • The density of lead is 11.342 g/cm3. What would be the volume of a 200.0 g sample of lead? V= m/D

  28. Using Scientific Measurements Notes Ch 2.3 Open your book to page 44

  29. How many grams of tin would occupy 5.5 L if it has a density of 7.264g/cm3? • Homework Check

  30. Dimensional Analysis Practice

  31. What’s the difference? Accuracy Precision How close measurements are to each other • How close a measurement is to the correct answer

  32. Percentage Error = Valueexperimental-Valueaccepted Valueaccepted Exp. Volume = 4.26mL Actual Volume= 4.15mL What is the % Error? X100% • The accuracy of an experimental value is compared to the accepted value. = Valueexperimental-Valueaccepted = 4.26 mL- 4.15mL X100% Valueaccepted 4.15 mL

  33. Let’s Do One more for Practice • Measured Value is D (iron) = 7.72 g/cm3 • Accepted Value is D (iron) = 7.87 g/cm3 = Valueexperimental-Valueaccepted • = 7.72 g/cm3 -7.87 g/cm3 X100% Valueaccepted • 7.87 g/cm3

  34. Significant Digits • numbers that occupy places for actual measurements • different tools allow for different accuracy and precision • significant digits allow for one uncertain or estimated digit

  35. What time is it? • Someone might say “1:30” or “1:28” or “1:27:55” • Each is appropriate for a different situation • In science we describe a value as having a certain number of “significant digits” • The # of significant digits in a value includes all digits that are certain and one that is uncertain • “1:30” has 2, 1:28 has 3, 1:27:55 has 5 • There are rules that dictate the # of significant digits in a value

  36. Sig Fig Rules Rules for using significant digits (a.k.a. sig. figs) • digits other than 0 are always significant • final 0s after a decimal point are always significant • zeros between digits are always significant • zeros used as place holders are not significant

  37. How many sig figs? ? ? ? ? ? ? ? ? ? ? ? ?

  38. Worksheet page 6 Significant Digits • Try section A on your own

  39. Answers to question A page 6 3 4 3 2 1 4 4 6 infinite 5 • 2.83 • 36.77 • 14.0 • 0.0033 • 0.02 • 0.2410 • 2.350 x 10–2 • 1.00009 • 3 • 0.0056040

  40. Note that a line overtop of a number indicates that it repeats indefinitely. E.g. 9.6 = 9.6666… • Similarly, 6.54 = 6.545454… Significant Digits • It is better to represent 100 as 1.00 x 102 • Alternatively you can underline the position of the last significant digit. E.g. 100. • This is especially useful when doing a long calculation or for recording experimental results • Don’t round your answer until the last step in a calculation.

  41. Adding with Significant Digits • Howfaris it fromToronto to room 72? • To room 75? • Adding a value that is much smaller than the last sig. digit of another value is irrelevant • When adding or subtracting, the # of sig. digits is determined by the sig. digit furthest to the left when #s are aligned according to their decimal.

  42. Adding with Significant Digits • Howfaris it fromToronto to room 229? To 225? • Adding a value that is much smaller than the last sig. digit of another value is irrelevant • When adding or subtracting, the # of sig. digits is determined by the sig. digit furthest to the left when #s are aligned according to their decimal. • E.g. a) 13.64 + 0.075 + 67 b) 267.8 – 9.36 13.64 267.8 + 0.075 – 9.36 + 67. 80.715 81 258.44 • Try question B on the handout

  43. i) ii) iii) 83.25 4.02 0.2983 – 0.1075 + 0.001 + 1.52 B Answers 83.14 4.02 1.82

  44. Multiplication and Division • Determining sig. digits for questions involving multiplication and division is slightly different • For these problems, your answer will have the same number of significant digits as the value with the fewest number of significant digits. • E.g. a) 608.3 x 3.45 b) 4.8  392 a) 3.45 has 3 sig. digits, so the answer will as well 608.3 x 3.45 = 2098.635 = 2.10 x 103 b) 4.8 has 2 sig. digits, so the answer will as well 4.8  392 = 0.012245 = 0.012 or 1.2 x 10–2 • Try question C and D on the handout (recall: for long questions, don’t round until the end)

  45. i) 7.255  81.334 = 0.08920 ii) 1.142 x 0.002 = 0.002 iii) 31.22 x 9.8 = 3.1 x 102 (or 310 or 305.956) i) 6.12 x 3.734 + 16.1  2.3 22.85208 + 7.0 = 29.9 iii) 1700 ii) 0.0030 + 0.02 = 0.02 + 134000 iv) 33.4 135700 =1.36 x105 + 112.7 + 0.032 146.132  6.487 = 22.5268 = 22.53 C and D Answers Note: 146.1  6.487 = 22.522 = 22.52

  46. i) 1.0 cm = 0.010 m ii) 0.0390 kg = 39.0 g iii) 1.7 m = 1700 mm or 1.7 x 103 mm E Answers

  47. Manipulating Sig Figs Adding and subtracting Multiplying and dividing Use the number of significant digits of the factor with the least number of sig figs. • Use the number of places after (or before) the decimal of the least precise number 43.01 + 4.0 . 47.0 . 200.0 + 4.0 204.0 43.01 x 4.00 172.0 . 43.01 x 4.00 170.0 . 200.1 + 4.0 200.0 204.1 - 24.8 179.0 43.01 x 4.00 200.0 . 10……. 4 43.01.

  48. Say it with me… • No Units No Points!

  49. 10 minutes to work onHomework Finish: Worksheets Page 6 Significant Digits Page 7 Dimensional Analysis Practice Book: Page 45 (1-2); 50 (1-4) Practice Page 54 (1-4) Practice ½ sheet quiz after this

  50. ½ sheet Quiz 2.3 Name Date Period • Convert 1.0cm into meters. • 0.0390 kg = _______ g • Express 1.7 m in mm. You must Use the correct Number of Significant Figures.. 0.010 m 39.0 g 1700 mm Or 1.7x103 m

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