Fehler:
H2O %2B NaOH %2B Sn %3D H2 %2B Na2%28Sn%28OH%294%29
^Unerwartets Zeichen ('%')H2O %2B NaOH %2B Sn %3D H2 %2B Na2%28Sn%28OH%294%29
^Unerwartets Zeichen ('%')