# chapter2 - Some possible answers are shown below. (a) C,...

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Homework Chapter 2 2.9 (a) Mass number = 12 + 15 = 27 (b) Mass number = 22 + 26 = 48 (c) Mass number = 30 + 32 = 62 2.14 electrons protons neutrons (a) 6 6 7 (b) 29 29 34 (c) 83 83 122 2.18 9 19 X, 9 20 X, and 9 21 X are isotopes of X 2.24 (d) 70% Actual value is 69.17% 2.28 (a) 4.24 mol Au · 197.0 g Au 1 mol Au = 835 g Au (b) 15.6 mol He · 4.003 g He 1 mol He = 62.4 g He (c) 0.063 mol Pt · 195 g Pt 1 mol Pt = 12 g Pt (d) 3.63 × 10 –4 mol Pu · 244.7 g Pu 1 mol Pu = 0.0888 g Pu 2.30 (a) 16.0 g Na · 1 mol Na 22.99 g Na = 0.696 mol Na (b) 0.876 g Sn · 1 mol Sn 118.7 g Sn = 7.38 × 10 –3 mol Sn (c) 0.0034 g Pt · 1 mol Pt 195 g Pt = 1.7 × 10 –5 mol Pt (d) 0.983 g Xe · 1 mol Xe 131.3 g Xe = 7.49 × 10 –3 mol Xe

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2.40 There are many correct answers for parts (a), (b), and (d).
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Unformatted text preview: Some possible answers are shown below. (a) C, carbon (c) Cl, chlorine (b) Na, sodium (d) Ne, neon 2.42 (a) Bk (b) Br (c) B (d) Ba (e) Bi 2.58 52 g Ga · 1 mol Ga 69.7 g Ga · 6.02 × 10 23 atoms Ga 1 mol Ga = 4.5 × 10 23 atoms Ga 9.5 g Al · 1 mol Al 27.0 g Al · 6.02 × 10 23 atoms Al 1 mol Al = 2.1 × 10 23 atoms Al 112 g As · 1 mol As 74.92 g As · 6.022 × 10 23 atoms As 1 mol As = 9.00 × 10 23 atoms As 2.68 atomic weight = ( 136 X mass)(% abundance) + ( 138 X mass)(% abundance) + ( 140 X mass)(% abundance) + ( 142 X mass)(% abundance) = (135.9090 u)(0.00193) + (137.9057 u)(0.00250) + (139.9053 u)(0.8848) + (141.9090 u)(0.1107) = 140.1046 u -- The element is cerium ....
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## This note was uploaded on 11/16/2011 for the course CHEM 1211k taught by Professor Wood during the Fall '07 term at Valdosta State University .

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chapter2 - Some possible answers are shown below. (a) C,...

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