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Scientific Measurement Did you do your homework? 44 points possible! The team with the most points at the end of the period wins! The wining team will receive 10 pts extra credit on their assignment sheets. Let’s Play! Accuracy and Prcesion Describe the accuracy and precision of each student’s measurement, the correct mass is 47.32 g. Trial Lissa Lamont 1 2 3 4 47.13 47.94 46.83 47.47 47.45 47.39 47.42 47.41 Leigh Anne 47.95 47.91 47.89 47.93 Answer Lissa – inaccurate and imprecise Lamont - accurate and precise Leigh - Anne inaccurate and precise Maximum 3 points Significant Figures a. b. c. d. How many in each? 60s = 1min 47.70 g of copper 1 km = 1000m 25 computers Answer a. b. c. d. Infinite 4 sig figs Infinite Infinite 4 points Round off to 3 Sig Figs a. b. c. d. 98.473 0.00076321 cg 57.048 m 12.17 oC Answer a. b. c. d. 98.5 0.000763 57.0 12.2 4 points Sig Fig Rules for Calculations Round of each of the answers correctly. a. 8.7 + 15.43 + 19 = 43.13 b. 853.2 – 627.443 = 225.757 c. 38.742 / 0.421 = 92.023 d. 5.4 x 3.21 x 1.871 = 32.431914 Answer a. b. c. d. 43 225.8 92.0 32 4 points Metric Conversions a. b. c. d. e. f. Make the following conversions 157 cs = ? s 42.7 L = ? ml 261 nm = ? mm 0.065 km = ? dm 642 cg = ? Kg 8.25 x102 cg = ? ng Answer a. b. c. d. e. f. 1.57 s 4.27 x 104 ml 2.61 x 10-4 mm 650 dm 0.00642 kg 8.25 x 109 ng 6 points Density Would the density of a person be the same on the surface of Earth and on the surface of the moon? Explain. Answer Yes, neither the mass nor volume of the person would change when they went to the moon, so the density (m/v) would remain the same. 5 points Scientific Notation Rank these numbers from smallest to largest. a. 5.3 x 104 b. 57 x 103 c. 4.9 x10-2 d. 0.0057 e. 5.1 x 10-3 f. 0.0072 x 102 Answer e, d, c, f, a, b 3 points Density The density of dry air measured at 25 oC is 1.19 x 10-3 g/cm3. What is the volume of 50.0 g of air? D = m / V, so V = m / D V= 5 points 50.0 g = 4.20 x 104 1.19 x 10-3 g/cm3 Density A tank with volume, 28.6 cm by 73.0 mm by 0.72 m is filled with olive oil. The oil in the tank has a mass of 1.38 x 104 g. What is the density of the olive oil in kilograms per liter? Answer First find the volume: 28.6 cm x 7.30 cm x 72 cm = 15032.16 cm = 15000 cm3 Second find the density: 1.38 x 104 g / 15000 cm3 = 0.92 g / cm3 = 0.92 kg / L 10 points