Practice_EXAM_I

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Unformatted text preview: ass (g) / molar mass (g/mole) = 64.2/32 = 2.003 16. What is the molar mass for calcium nitrate, Ca(NO3)2? (a) 44 (b) 56 (c) 87 (d) 93 (e) 164 Hint: For 11th ed.: p.p. 81‐82 and Example 3.5; for 9th edition: p.p. 83‐84. Example 3.5. For 10th edition: p.p. 85‐87 Example 3.5. In the formula, Ca(NO3)2, it indicates there are 1 Ca, 1x2 = 2 N and 3x2 = 6 O. Go to the periodic table and locate the atomic mass for each atom. Thus the formula mass of Ca(NO3)2 = 1x40 + 2x14 + 6x16 = 164 17. How many hydrogen atoms are there in 48.0 g of CH4? (b) 7.22x1024 (c) 6.02x1023 (d) 1.20x1025 (e) 4.70x1025 (a) 1.81x1023 th th Hint: For 11 ed.: p. 83 and Example 3.7; for 9 edition: p. 85 and Example 3.7. For 10th edition: p. 87 and Example 3.7. According to the chemical formula, one mole of CH4 contains 1 mole of C atoms and 4 moles of hydrogen atoms. Thus, the mole of H = 4 x {mass of CH4/molar mass of CH4}. When converting moles into atoms, it needs to multiply the Avogadro’s number, that is, 6.02x1023. Thus the numb...
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