Homework%20SolutionsChpt3

Homework%20SolutionsChpt3 - Chapter 3 Homework Solutions...

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Chapter 3 Homework Solutions 4. (a) Molecular formula of pyruvic acid is C 3 H 4 O 3 . (b) Molecular formula of isocitric acid is C 6 H 8 O 7 . 12. 18 gal × 3790 mL 1 gal × 1cm 3 1mL × 0.692 g 1cm 3 = 4.7 × 10 4 g 4.7 × 10 4 g × 1lb 453.59 g = 1.0 × 10 2 lb 14. (a) Benzene Molecular Formula: C 6 H 6 (b) Vitamin C Molecular Formula: C 6 H 8 O 6 20 . A general rule for the charge on a metal cation: the group number represents the number of electrons lost. Hence, the group number will be the cation’s positive charge. (a) Lithium (Group 1A) Li + (b) Strontium (Group 2A) Sr 2+ (c) Aluminum (Group 3A) Al 3+ (d) Calcium (Group 2A) Ca 2+ (e) Zinc (Group 2B) Zn 2+ 21. For nonmetal elements in Groups 5A-7A, the electrons gained by an atom to form a stable anion are calculated using the formula: 8 – (group number). That means the (group number) – 8 is the negative charge of the anion. (a) nitrogen (Group 5A) 5 – 8 = –3 N 3– (b) sulfur (Group 6A) 6 – 8 = –2 S 2– (c) chlorine (Group 7A) 7 – 8 = –1 Cl (d) iodine (Group 7A) 7 – 8 = –1 I (e) phosphorus (Group 5A) 5 – 8 = –3 P 3– 22 . Barium (Group 2A) has a +2 charge. Bromine (Group 7A) has a –1 charge. So, the ions are Ba 2+ and Br . 24 . (a) selenium (Group 6A) 6 – 8 = –2 Se 2– (b) fluorine (Group 7A) 7 – 8 = –1 F (c) nickel (a transition metal) Ni 2+ (d) nitrogen (Group 5A) 5 – 8 = –3 N 3– 27. (a) Aluminum ion (from Group 3A) is Al 3+ . Chloride ion (from Group 7A) is Cl . AlCl is not a neutral combination of these two ions. The proper formula would be AlCl 3 . [net charge = +3 + 3 × (–1) = 0 ] (b) Sodium ion (Group 1A) is Na + . Fluoride ion (from Group 7A) is F . NaF 2 is not a neutral combination of these two ions. The proper formula would be NaF. [net
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charge = +1 + (–1) = 0 ] (c) Gallium ion (from Group 3A) is Ga 3+ . Oxide ion (from Group 6A) is O 2– . Ga 2 O 3 is the proper neutral combination of these two ions. [net charge = 2 × (+3) + 3 × (–2) = 0 ] (d) Magnesium ion (from Group 2A) is Mg 2+ . Sulfide ion (from Group 6A) is S 2– . MgS is the proper neutral combination of these two ions. [net charge = +2 + (–2) = 0 ] 28 . (a) Calcium ion (from Group 2A) is Ca 2+ . Oxide ion (from Group 6A) is O 2– . Ca 2 O is not a neutral combination of these two ions. The proper formula would be CaO. [net charge = +2 + (–2) = 0] (b) Strontium ion (Group 2A) is Sr 2+ . Chloride ion (from Group 7A) is Cl . SrCl 2 is the proper neutral combination of these two ions. [net charge = +2 + 2 × (–1) = 0] (c) Iron ion (from the transition elements) is Fe 3+ or Fe 2+ . Oxide ion (from Group 6A) is O 2– . Fe 2 O 5 is not a neutral combination of these ions. The proper possible formulas would be FeO [net charge = +2 + (–2) = 0] or Fe 2 O 3 [net charge = 2 × (+3) + 3 × (–2) = 0] (d) Potassium ion (from Group 1A) is K + . Oxide ion (from Group 6A) is O 2– . K
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This note was uploaded on 09/13/2008 for the course CHEM 1410 taught by Professor Acree during the Spring '08 term at North Texas.

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Homework%20SolutionsChpt3 - Chapter 3 Homework Solutions...

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