Practice_EXAM_I

Gototheperiodictable

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Unformatted text preview: 467 (b) 9.966 (c) 10.042 (c) 10.504 (e) 10.810 th th Hint: For 11 ed.: p.p. 76‐77 and Example 3.1; for 9 edition: p.p. 78‐79. Example 3.1; 10th edition: p.p. 80‐81 Example 3.1. You must convert the % into decimals first and then apply the formula and memorize it: M = M1X1 + M2X2 = 10.0129x0.1978 + 11.0093x0.8022 = 10.810. Note that the average atomic mass (with decimal) can be found in the periodic table, while the mass number (a whole number) can not be found. For three isotopes: Example Exercise 5.3: 28Si (27.977 amu; 92.21% abundance), 29Si (28.976 amu; 4.70% abundance) and 30Si (29.974 amu; 3.09% abundance). The atomic mass M = M1X1 + M2X2 + M3X3 = 27.977x0.9221 + 28.976x0.0470 + 29.974x0.0309 = 28.09 amu by rounding to two decimals. 15. How many moles of S are there in 64.2 g of S? (a) 1.325 (b) 1.764 (c) 1.968 (d) 2.003 (e) 2.475 Hint: For 11th ed.: Example 3.2 and Example 3.6; for 9th edition: p. 81. Examples 3.2 and 3.6. For 10th edition: p.p. 82‐83: Example 3.2. Mole = m...
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This note was uploaded on 01/25/2014 for the course CHEM 1411 taught by Professor None during the Fall '11 term at HCCS.

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