Error:
MgCO3 %2B CaCO3 %2B HCl %3D Mg%28OH%292 %2B CaCl2 %2B CO2
^
Unexpected character ('%')MgCO3 %2B CaCO3 %2B HCl %3D Mg%28OH%292 %2B CaCl2 %2B CO2
^
Unexpected character ('%')