posted by Anonymous .
Will a precipitate form when an aqueous solution of (NH4)4CO3 is mixed with Fe(NO3)3
Probably so but it probably will not be Fe2(CO3)3. Most likely the ppt will be Fe(OH)3. However, one must remember that high concns of NH4^+ [you're adding (NH4)2CO3] reduces the OH^- in solution and hydroxide ppts sometimes don't appear.