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                    9.3.   The names of some common polyatomic ions are in    10.2.   (a) CuSO 4

                          Table 9.3. Using this table as a reference, the names are
                                                                                     1 of Cu = 1 × 63.5 u = 63.5 u
                          (a) hydroxide         (d) nitrate
                                                                                      1 of S = 1 × 32.1 u = 32.1 u
                          (b) sulfi te          (e) carbonate
                                                                                     4 of O = 4 × 16.0 u = 64.0 u
                          (c) hypochlorite      (f) perchlorate
                                                                                                    159.6 u
                    9.4.   The Roman numeral tells you the charge on the variable-charge

                                                                                 (b) CS 2
                          elements. The charges for the polyatomic ions are found in

                          Table 9.3. The charges for metallic elements can be found in      1 of C = 1 × 12.0 u = 12.0 u

                          Tables 9.1 and 9.2. Using these resources and the crossover      2 of S = 2 × 32.0 u = 64.0 u
                          technique, the formulas are as follows:                                    76.0 u
                          (a) Fe(OH) 3          (d) NH 4 NO 3
                                                                                 (c) CaSO 4
                          (b) Pb 3 (PO 4 ) 2    (e) KHCO 3
                                                                                     1 of Ca = 1 × 40.1 u = 40.1 u
                          (c) ZnCO 3            (f) K 2 SO 3
                                                                                      1 of S = 1 × 32.0 u = 32.0 u
                    9.5.   Table 9.7 has information about the meaning of prefi xes and      4 of O = 4 × 16.0 u = 64.0 u
                          stem names used in naming covalent compounds. For example,                136.1 u
                          (a) asks for the formula of carbon tetrachloride. Carbon has no

                          prefixes, so there is one carbon atom, and it comes first in the   (d) Na 2 CO 3


                          formula because it comes first in the name. Th e tetra- prefi x      2 of Na = 2 × 23.0 u = 46.0 u
                          means four, so there are four chlorine atoms. The name ends in      1 of C = 1 × 12.0 u = 12.0 u

                          -ide, so you know there are only two elements in the compound.      3 of O = 3 × 16.0 u = 48.0 u

                          The symbols can be obtained from the list of elements on the              106.0 u
                          inside back cover of this text. Using all this information from
                                                                           10.3.   (a) FeS 2
                          the name, you can reason out the formula for carbon
                                                                                       (55.9 u Fe)(1)
                          tetrachloride. The same process is used for the other compounds   __

                                                                                                 ×
                                                                                 For Fe:                100% FeS 2  = 46.6% Fe

                          and  formulas:                                               119.0 u FeS 2
                          (a) CCl 4             (d) SO 3                              __
                                                                                      (32.0 u S)(2)
                                                                                               ×

                          (b) H 2 O             (e) N 2 O 5                      For S:             100% FeS 2  = 53.4% S
                                                                                      119.9 u FeS 2
                          (c) MnO 2             (f) As 2 S 5
                                                                                 or (100% FeS 2 ) – (46.6% Fe) = 53.4% S
                     9.6.  Again using information from Table 9.7, this question requires
                          you to reverse the thinking procedure you learned in question 9.5.  (b) H 3 BO 3
                                                                                       (1.0 u H)(3)
                          (a) carbon monoxide   (d) dinitrogen monoxide               __
                                                                                                ×

                                                                                 For H:            100% H 3 BO 2  = 4.85% H


                          (b) carbon dioxide    (e) tetraphosphorus trisulfi de       61.8 u H 3 BO 3
                          (c) carbon disulfi de   (f) dinitrogen trioxide             __
                                                                                      (10.8 u B)(1)

                                                                                 For B:             × 100% H 3 BO 3  = 17.5% B

                    9.7.   The types of bonds formed are predicted by using the       61.8 u H 3 BO 3

                            electronegativity scale in Table 9.5 and finding the absolute   __

                                                                                       (16 u O)(3)
                                                                                                ×


                                                                                 For O:            100% H 3 BO 3  = 77.7% O


                          difference. On this basis:                                  61.8 u H 3 BO 3
                          (a) Diff erence = 1.7, which means ionic bond
                          (b) Diff erence = 0, which means covalent              (c) NaHCO 3
                                                                                        (23.0 u Na)(1)
                          (c) Diff erence = 0, which means covalent                    __


                                                                                 For Na:             × 100% NaHCO 3  = 27.4% Na
                          (d) Diff erence = 0.4, which means covalent                  84.0 u NaHCO 3
                          (e) Diff erence = 3.0, which means ionic                    __
                                                                                        (1.0 u H)(1)


                          (f)  Diff erence = 1.6, which means polar covalent and almost      For H:              × 100% NaHCO 3  = 1.2% H
                                                                                       84.0 u NaHCO 3
                             ionic
                                                                                      __
                                                                                        (12.0 u C)(1)

                                                                                 For C:              × 100% NaHCO 3  = 14.3% C

                                                                                      84.0 u NaHCO 3
                    CHAPTER 10                                                        __
                                                                                        (16.0 u O)(3)
                                                                                 For O:              × 100% NaHCO 3  = 57.1% O


                    10.1.   (a)  MgCl 2  is an ionic compound, so the formula has to be   84.0 u NaHCO 3
                             empirical.
                                                                                 (d) C 9 H 8 O 4
                          (b)  C 2 H 2  is a covalent compound, so the formula might be
                                                                                        (12.0 u C)(9)

                             molecular. Since it is not the simplest whole number ratio      For C:     __
                                                                                                  × 100% C 9 H 8 O 4  = 60.0% C

                             (which would be CH), then the formula is  molecular.     180.0 u C 9 H 8 O 4
                                                                                        (1.0 u H)(8)
                          (c)  BaF 2  is ionic; the formula is empirical.             __

                                                                                 For H:             × 100% C 9 H 8 O 4  = 4.4.% H

                          (d)  C 8 H 18  is not the simplest whole number ratio of a covalent   180.0 u C 9 H 8 O 4
                             compound, so the formula is molecular.                   __
                                                                                        (16.0 u O)(4)


                          (e)  CH 4  is covalent, but the formula might or might not be      For O:              × 100% C 9 H 8 O 4  = 35.6% O
                                                                                       180.0 u C 9 H 8 O 4
                             molecular  (?).
                          (f)  S 8  is a nonmetal bonded to a nonmetal (itself); this is a
                             molecular formula.
                   666     APPENDIX E  Solutions for Group A Parallel Exercises                                         E-24
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