Oxidation-Reduction

 

  4) (a)

                  +3 -3          +2  -2                  +3 +3 -6
                        -1          +1  -2                  +1      -2         +1 -1

               PBr3 + 3H2O H3PO3 + 3HBr

               This is not an oxidation-reduction reaction because there is no change in oxidation states.

 

      (b)

                                                                 +1 +5 -6
                   +1 -1       +1 -2 +1                          -2         +1 -1

               NaI + 3HOCl NaIO3 + 3HCl

 

                                             -1               +5                                                     +1                   -1

               oxidation:   I I                    reduction:   Cl Cl

 

      (c)

                     +4 -4         +1+5-6         +2 -2                      +2 +6-8
                           -2                  -2         +1 -2                      +1      -2       +2 -2                

               3SO2 + 2HNO3 + 2H2O 3H2SO4 + 2NO

 

                                            +4               +6                                                     +5                +2

               oxidation:   S S                     reduction:   N N

 

      (d)

                     +2 +6 -8                                                    +4 -4      +2  +6 -8          +2  -2
                     +1       -2         +1   -1                      0             -2      +1        -2         +1  -2            

               2H2SO4 + 2NaBr Br2 + SO2 + Na2SO4 + 2H2O

 

                                               -1                   0                                                        +6               +4

               oxidation:   Br Br2                     reduction:   S S