Fehler:
H2S %2B Fe2%28SO4%293 %3D H2SO4 %2B S %2B FeSO4
^Unerwartets Zeichen ('%')H2S %2B Fe2%28SO4%293 %3D H2SO4 %2B S %2B FeSO4
^Unerwartets Zeichen ('%')