Error:
Cr2O7%3A2- %2B H%3A%2B %2B I%3A- %3D Cr %2B I2 %2B H2O
^Unexpected character ('%')Cr2O7%3A2- %2B H%3A%2B %2B I%3A- %3D Cr %2B I2 %2B H2O
^Unexpected character ('%')