posted by Anonymous .
I am having trouble with equation writing and complex ions. Please help.
Ag+ + NH3(excess)---> ?
Fe^3+ + SCN- ---> ?
Cr^3+ + OH-(excess) ---> ?
Cr(OH)3(s) + H+ ----> ?
Cr(OH)4- + H202 + OH- ---> ?
Zn2+ + K+ + Fe(CN)6^4- --> ?
I'm not helping if I write these for you. What is it you don't understand?
A general rule, not always followed, is that the complexing agent is twice the valence. That is
Ag^+ + 2NH3 ==> Ag(NH3)2^+
Many of the OH complexes add one OH; as in
Cr(OH)3 + OH^- ==> Cr(OH)4^- and
Al(OH)3 + OH^- ==> Al(OH)4^-
The easiest thing to do is to memorize them. I think most of us have done that during usage through the years.