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Thursday!!!!! 9 /1/11

Thursday!!!!! 9 /1/11. Bell Ringer. Schedule. PAP Chemistry. Bell Ringer Numbers in Science Lab Who Are You??. HOMEWORK: Metric, Sig Fig, Dimensional Anaylysis quiz tomorrow!!. I CAN……accurately perform measurements in the lab utilizing sig figs.

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Thursday!!!!! 9 /1/11

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  1. Thursday!!!!!9/1/11 Bell Ringer Schedule PAP Chemistry • Bell Ringer • Numbers in Science Lab • Who Are You?? HOMEWORK: Metric, Sig Fig, Dimensional Anaylysis quiz tomorrow!! I CAN……accurately perform measurements in the lab utilizing sig figs Teachers open the door, but you must enter by yourself  • Get out your Numbers in Science lab, your notes from yesterday, and complete your lab. Turn it in to your tray when you are finished. • What have you heard about a mutant strain of the Bird Flu?

  2. MetricsKilo Hecta Deca Base Unit Deci Centi Milli1000 100 10 g, L, m .1 .01 .001 • Convert the following using the metric system: • A. 45 mL to dL • B. 200 g to kg • C. 4200 mm to m

  3. Dimensional Analysis“Factor Label Method” • 5 hrs to sec • 4 miles to in 5,280 ft. = 1mile 1 ft = 12 in. • 5 moles to Liters 1 mole = 22.4 liters • 50 cm3 to m3 • 20 kg/m3 to g/cm3

  4. Scientific Notation • Convert to Scientific Notation • 0.25 • 0.025 • 0.0025 • 5050

  5. Convert to Standard Notation • 1 x 104 • 1 x 10-4 • 2.2x 102

  6. Significant Figures • Counting Sig Figs • Count all numbers EXCEPT: • Leading zeros -- 0.0025 • Trailing zeros without a decimal point -- 2,500

  7. Significant Figures Counting Sig Fig Examples 1. 23.50 1. 23.50 4 sig figs 3 sig figs 2. 402 2. 402 3. 5,280 3. 5,280 3 sig figs 2 sig figs 4. 0.080 4. 0.080

  8. Identify the # of Significant Figures • 0.02 • 0.020 • 501 • 501.0 • 5000 • 5.000 • 0.00470 • 0.47000

  9. 3 SF Significant Figures • Calculating with Sig Figs • 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 • “1” in any conversion: 1 in = 2.54 cm • Multiply/Divide - The # with the fewest sig figs determines the # of sig figs in the answer. (13.91g/cm3)(23.3cm3) = 324.103g 4 SF 3 SF 324g

  10. Significant Figures • Calculating with Sig Figs (con’t) • Add/Subtract - The # with the lowest decimal value determines the place of the last sig fig in the answer. 224 g + 130 g 354 g 224 g + 130 g 354 g 3.75 mL + 4.1 mL 7.85 mL 3.75 mL + 4.1 mL 7.85 mL  354 g  7.9 mL C. Johannesson

  11. Calculating % error • Experimental = 1.24 g • Accepted = 9.98 g • % error =?

  12. M V M D = D V C. Derived Units • Combination of base units. 1 cm3 = 1 mL 1 dm3 = 1 L • Density - mass per unit volume (g/cm3)

  13. Significant Figures • Indicate accuracy of a measurement as will as the measuring capacity of the instrument used. • Recording Sig Figs • Sig figs in a measurement include the known digits plus a final estimated digit 2.35 cm C. Johannesson

  14. Numbers in Science Lab Tips Advice Show your math work on a separate sheet of paper with UNITS and CIRCLE your final answer. Remember your SIG FIGS!! • Conversions: • 454 g = 1 lb. • 2.54 cm = 1 in • 16 oz = 1 lb. • Density = Mass/Volume • Volume: length x width x height (Use any time you use a ruler) • Circumference: C = ∏d (Question 10) • Diameter: d = 2r (Question 11) • V = Vfinal- Vinital (Use any time you do water displacement) • Volume of a sphere: (Question 12) • V= 4/3 ∏r3

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