Answers and Explanations

REVIEW QUESTIONS

1 . D

Avogadro’s  number  (6.022  ×   10^23 ) defines the number  of  particles   present in  1   mole    of

anything.   So  there   are 6.022   ×   10^23   electrons   in  1   mole    of  electrons.

2 . B

The reduction   of  one mole    of  Ni2+    to  1   mole    of  Ni  (s) requires    2   moles   of  electrons.  The transfer

of  1   mole    of  electrons   is  equivalent  to  the transfer    of  1   F   of  charge. Therefore,  since   2   moles   of

electrons   are required    to  reduce  1   mole    of  Ni2+,   2   F   are required.

3 . B

In  order   to  solve   this    problem,    first   determine   the number  of  moles   of  Au  present in  0.600   g.

Next,   determine   the number  of  moles   of  electrons   used    to  reduce  Au3+    (aq)    to  0.00300 mol of

Au  (s).    From    the given   reduction   half-reaction   of  Au, it  is  evident that    for every   mole    of  Au3+,   3

moles   of  electrons   are transferred in  order   to  produce 1   mole    of  Au  (s);    therefore,

Finally,    convert 0.00900 mol e−  to  its equivalent  in  C: