Ошибка:
FeCl2 %2B K3%5BFe%28CN%296%5D %3D KCl %2B Fe3%5BFe%28CN%296%5D2
^Неизвестный знак ('%')FeCl2 %2B K3%5BFe%28CN%296%5D %3D KCl %2B Fe3%5BFe%28CN%296%5D2
^Неизвестный знак ('%')