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DO NOW…. Which liquid has the highest density?

1. 3. 2. 4. 5. DO NOW…. Which liquid has the highest density?. least dense 1 < 3 < 5 < 2 < 4 most dense. Coussement, DeSchepper, et al. , Brain Strains Power Puzzles 2002, page 16. Brick. Styrofoam. Density is an INTENSIVE property of matter.

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DO NOW…. Which liquid has the highest density?

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  1. 1 3 2 4 5 DO NOW….Which liquid has the highest density? least dense 1 < 3 < 5 < 2 < 4 most dense Coussement, DeSchepper, et al. , Brain Strains Power Puzzles2002, page 16

  2. Brick Styrofoam • Density is an INTENSIVEproperty of matter. • - does NOT depend on quantity of matter. • Examples: • color, melting point, boiling point, odor, density Gold • DIFFERENT THAN • EXTENSIVE properties - depends on quantity of matter. - mass, volume, length

  3. M V D = M ass M D D V V = ensity olume Density M = DV

  4. The heaviest human brain ever recorded had a mass of 2.3kg. How many micrograms is that? 2.3 kg 1000 g 1 x 106 µg = 1 kg 1 g 2.3 x 109 µg

  5. The density of lead is 11.34 g/cm3. Find the density of lead in kg/m3 11.34 g 1 kg 100 cm 100 cm 100 cm = cm3 1000 g 1 m 1m 1m 11,340 kg m3

  6. The average concentration of testosterone in the blood of a male in his twenties is 550 nanograms per deciliter. How many grams per cubic centimeter does this concentration represent? 550 ng 1 g 10 dL 1 L 1 mL = dL 1 x 10 9 ng 1 L 1000 mL 1 cm3 5.5 x 10-9g cm3

  7. Density of Some Common Substances Density of Some Common Substance Substance Density (g / cm3) Air 0.0013* Lithium 0.53 Ice 0.917 Water 1.00 Aluminum 2.70 Iron 7.86 Lead 11.4 Gold 19.3 *at 0oC and 1 atm pressure

  8. Consider Equal Masses Equal masses… …but unequal volumes. The object with the larger volume (aluminum cube) has the density. gold aluminum smaller Christopherson Scales Made in Normal, Illinois USA Dorin, Demmin, Gabel, Chemistry The Study of Matter , 3rd Edition, 1990, page 71

  9. cork ice aluminum 2.7 Comparing Densities (g/cm3) 0.25 0.9 water 1.0 Jaffe, New World of Chemistry, 1955, page 66

  10. M V D = 0.196 g 100. mL 1.96 x 10-3 g/mL Density Practice Problems • What is the density of carbon dioxide gas if 0.196 g occupies a volume of 100. mL?

  11. 1.75 g/mL x 5.0 mL 8.8g Density Practice Problems • An irregularly shaped stone has a volume of 5.0 mL. The density of the stone is 1.75 g/mL. What is the mass of this stone? M = D x V

  12. M D V = 94 g 7.8 g/cm3 12 cm3 Density Practice Problems • A sample of iron has a mass of 94 g and a density of 7.8 g/cm3. What is the volume of the iron?

  13. SI Prefixes mega- 1,000,000 kilo- 1,000 deci- 1/10 centi- 1/100 milli- 1/1,000 micro- 1/1,000,000 Also know… 1 mL = 1 cm3

  14. 1 2 3 4 5 0 cm 1 2 3 4 5 0 cm 1 2 3 4 5 0 cm Practice Measuring 4.5 cm 4.54 cm 3.0 cm Timberlake, Chemistry 7th Edition, page 7

  15. 20 15.0 mL 15 mL ? 10

  16. 60oC 100oC 50oC 25oC 80oC 40oC 20oC 60oC 30oC 15oC 40oC 20oC 10oC 20oC 10oC 5oC 0oC 0oC 0oC 30.0oC 19.0oC A C E Practice Recording Temperature(Celcius) 60.oC

  17. Scientific Notation • Calculating with scientific notation (5.44 × 107 g) = ?? (8.1 × 104 mol) Type on your calculator: 4 5.44 7 8.1 ÷ EE EE = = 671.6049383 = 670 g/mol = 6.7 × 102 g/mol Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

  18. Scientific Notation • Converting into scientific notation: • Move decimal until there’s 1 digit to its left. Places moved = exponent. • Large # (>1)  positive exponentSmall # (<1)  negative exponent • Only include sig. figs. 65,000 kg  6.5 × 104 kg Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

  19. 2,400,000 g 0.00256 kg 7  10-5 km 6.2  104 mm Scientific Notation Practice Problems 2.4  106 g 2.56  10-3 kg 0.00007 km 62,000 mm Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

  20. Significant figures: Rules for zeros Leading zeros are not significant. Leading zero – three significant figures 0.421 Captive zeros are significant. Captive zero 4012 – four significant figures Trailing zeros are significant. Trailing zero 114.20 – five significant figures

  21. Significant Figures • Counting Sig Figs • All digits are significant EXCEPT… • Leading zeros -- 0.0025 • Trailing zeros without a decimal point -- 2,500 Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

  22. Significant Figures • Calculating with Sig Figs (con’t) • Exact Numbers do not limit the # of sig figs in the answer. • Counting numbers: 12 students • Exact conversions: 1 m = 100 cm Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

  23. 3 SF Significant Figures • Calculating with Sig Figs • Multiply/Divide - The # with the fewest sig figs determines the # of sig figs in the answer. (13.91g/cm3)(23.3cm3) = 324.103g 3 SF 4 SF 324g Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

  24. Significant Figures • Calculating with Sig Figs • Add/Subtract - The # with the fewest places after the decimal point determines the # of sig figs in the answer. 18.9 g - 0.84 g  18.1 g 18.06 g Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

  25. (15.30 g) ÷ (6.4 mL)  2.4 g/mL 2 SF Significant Figures Practice Problems 4 SF 2 SF = 2.390625 g/mL 18.9 g - 0.84 g  18.1 g 18.06 g Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem

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