Thanks for your reply Daniel.
When you balance a redox reaction, you have to know whether the solution is acidic (H+) or alkaline (OH-). That will determinate if you have to balance the equation with H+ ions or OH- ions. If I just enter the chemical equation:
MnO4^- + SnO2^-2 = MnO2 + SnO3^-2
Then Wolfram does not know how to balance the redox reaction. How can I tell the computer to balance a redox reaction, and at the same time tell it, that the solution is acidic or alkaline in the input field?
Thanks!