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# PracticeSheet2Br-DrAnswersBT +REVISED+ jayson (1) - ×...

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Practice Sheet 2 2B.1 a) 5.5 × 10 7 g b) 3.4 × 10 –3 L c) 3.3 × 10 –8 mmol d) 2.73 × 10 15 ng 2B.2 (1 dm 3 ) kg 1 lbs. 2.2046 g 1000 kg 1 mL 1 g 19.31 L 1 mL 1000 dm 1 L 1 3 = 42.57 lb. 2B.3 atoms 3 atoms 10 x 6.022 C mol 1 C mol 1 C g 12.000 23 = 6.0 × 10 -23 g 2D.1 Assume 1 mol of 238 U weighs approximately 238 g 2.13 mg × 1 mol × 1 g × 6.022 x 10 23 atoms × 146 n = 7.87 × 10 20 neutrons 238 g 1000 mg 1 mol atom 2D.2 In the sample, there are 30 g Au and therefore 70 g Na. # e in Au = 30g Au × 1 mol × 6.022 x 10 23 atoms × 79 e = 7.2 × 10 24 e 197.0 g mol atom #e in Na = 70g Na × 1 mol
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Unformatted text preview: × 6.022 x 10 23 atoms × 11 e = 2.0 × 10 25 e 22.99 g mol atom Total #e = 7.2 x 10 24 + 2.0 x 10 25 = 2.7 × 10 25 e If we are very strict with significant digits, we should report the answers with significant digits (from 30 %), or 3 x 10 25 e. 2D.3 see back of BLB text 2D.4 (a) (10 cm) 3 → 1000cm 3 amu 197 atom 1 1.6605x10 amu 1 cm g 19.3 24-3 g = 5.90 × 10 25 atoms (b) 5.90 × 10 25 atoms × (79e-/ atom) = 4.66 × 10 27 electrons...
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