ANS_EX_3 - Swieter; p1 of 8 CHM1040 Answer to Exercise Set...

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Swieter; p1 of 8 X:\~Natsci\ADJUNCT\bhaskar\pdf\1041\ANS_EX#3.DOC CHM1040 Answer to Exercise Set 3 QUESTIONS ON BONDING, IONS AND MOLECULES 1.An atom is the smallest uncharged particle of an element that retains the identity of that element. A molecule is the smallest (uncharged) particle of a substance that retains the composition and properties of that substance AND is capable of independent existence. 2.An atom is the smallest uncharged particle of an element that retains the identity of that element. A simple cation is created when a single atom loses one or more electrons (e.g., Na + or Mg +2 ). A simple anion is created when a single atom gains one or more electrons (e.g., Cl - or O -2 ). 3.A molecule is the smallest (uncharged) particle of a substance that retains the composition and properties of that substance AND is capable of independent existence. A polyatomic ion is a group of atoms that have gained ( to form a polyatomic anion) or lost electrons ( to form a polyatomic cation). 4.A covalent bond is formed when two atoms share (usually two) electrons. Ionic bond formation is initiated when the atoms of one element each lose one or more electrons (to form cations) and the atoms of a different element each gain one or more electrons (to form anions). The mutual attraction between the collection of anions and cations to form a solid is called ionic bonding. 5. a) Ionic (Na is a metal element and Cl is a nonmetal element). a. Covalent (C and H are both nonmetal elements). b. Covalent (B and Cl are both nonmetal elements). c. Ionic (Fe is a metal element and O is a nonmetal element). 6. a) The correct formula for carbon dioxide is CO 2 (NOT CO2). a. The molecule of H 2 O actually contains two hydrogen atoms and one oxygen atom (NOT one hydrogen atom and two oxygen atoms). b. Sodium chloride is an ionic substance and therefore DOES NOT contain molecules. The formula unit of sodium chloride has a formula of NaCl. c. Mg +2 is a cation (NOT an anion). d. NH 3 is a molecule (NOT an ion; NH 3 has no charge).
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Swieter; p2 of 8 X:\~Natsci\ADJUNCT\bhaskar\pdf\1041\ANS_EX#3.DOC QUESTIONS ON MOLES, FORMULAS AND PERCENT COMPOSITION 7.a. Fe, 55.84 g/mol b. N 2 O 4 , 92.0 g/mol c. (NH 4 ) 3 AsO 4 , 193.03 g/mol d. CO 3 -2 , 60.01 g/mol 8.a. Fe, i) 55.84 amu ii) 55.84 5 amu x 1.66054 x 10 -24 g/amu = 9.273 x 10 -23 g g 10 x 9.273 = 10 x 6.02214 mol 1 x g/mol 84 55. or 23 - 23 5 b. N 2 O 4 , i) 92.0 amu ii) 92.0 1 amu x 1.66054 x 10 -24 g/amu = 1.53 x 10 -22 g g 10 x 1.53 = 10 x 6.02214 mol 1 x g/mol 0 92. or 22 - 23 1 c. (NH 4 ) 3 AsO 4 , i) 193.03 amu ii) 193.03 4 amu x 1.66054 x 10 -24 g/amu = 3.2054 x 10 -22 g g 10 x 3.2054 = 10 x 6.02214 mol 1 x g/mol 03 193. or 22 - 23 4 d. CO 3 -2 , i) 60.01 amu ii) 60.00 9 amu x 1.66054 x 10 -24 g/amu = 9.965 x 10 -23 g g 10 x 9.965 = 10 x 6.02214 mol 1 x g/mol 00 60. or 23 - 23 9 9.a. O H mol 2.08 = g 18.0152 mol 1 x O H g 37.5 2 2 b. F
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ANS_EX_3 - Swieter; p1 of 8 CHM1040 Answer to Exercise Set...

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