Practice_EXAM_I

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Unformatted text preview: er of H atoms = moles of H atoms x Avogadro’s number = (6.02x1023)x{4x(48.0/16.0)} = 7.22x1024 18. What is the mass percent (%) for O in SO2? (a) 38.09 (b) 45.41 (c) 50.00 (d) 53.86 (e) 56.43 Hint: For 11th ed.: p.p. 85‐86 and Example 3.8; for 9th edition: p. 87: Equation (3.1); for 10th edition: p.p. 88‐89: Example 3.8. % S = (mass of 2 O/ mass of SO2) x 100% = {2x16/(1x32+2x16)}x100% = 50.0% 3 19. Chemical analysis shows the composition of a compound containing carbon, hydrogen, chlorine, and oxygen, to be 37.84% C, 2.12% H, 55.84% Cl, and 4.20% O. What is its empirical formula? (c) C12H8Cl6O (d) C12H8Cl6O4 (a) CHClO (b) C2HClO4 Hint: For 11th ed.: p.p. 86‐89: Examples 3.9 and 3.11. For 9th edition: p. 88. Example 3.9 (Vitamin C): very important or the most difficult for empirical formula calculation. Figure 3.5. or p. 109 (3.50). For 10th edition: p.p. 92‐94: Example 3.9 (p. 90). The empirical formula is the simplest integral ratio of moles among each atom. Here, there are four different kinds of a...
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