[viera123]

1. How to predict the colour of salts or metals?

2. When will electrode dissolve into electrolyte?

[DevaDevil]

colors are hard to predict. Most crystalline salts are transparent, where more amorphous salts tend to be opaque.

Some salts from a certain metal have a tendency to be a certain color when soluted, like a copper salt tends to be blueish in water. Nickel salts tend to be greenish. etc.

But for chromium salts / complexes for example you have a color range. Yellow, orange, green


As for when will an electrode dissolve: I gather you mean a metallic electrode?
In that case it will dissolve if the open circuit potential of the cell is enough for the metal to oxidise. In other words if there is a counter reaction to M --> M⁺ + e^- with the right potential to make the reaction possible. Look at the contents of your cell and grab a table of reduction potentials to check that.

Some special complexing reactions will not be noted though (like Pd will dissolve slowly in a nitride solution), but most basic oxidations are in there.

[ARGOS++]

Dear Viera123;

Don’t forget that you can force the electrode to the electrolyte with the same reaction equation by using an outer electrical potential (= electroplating) of correct polarity.


Good Luck!
                   ARGOS⁺⁺