darkflame89 - 18-10-2004 at 01:03
I am a bit confused about certain things in electrochemistry, moreover the textbooks do not seem to address such stuff. I would like to clarify
certain things.
We know that pure distilled water does not conduct electricity, but if you add a bit of ionic salt to it, it will conduct electricity, with hydrogen
from the cathode and oxygen gas from the anode. But how does this mechanism occur? I mean does the ions themselves know in what priority to are they
reduced or oxidised?
Is it correct if I say it like this: Say when sodium chloride is dissolved in water, the water molecules are immediately attracted towards the ions,
and force the lattice of ions apart, forming a sort of cage around the ions. So now we put two electrodes to the solution, and connect to a DC
current. The cage of water molecules containing the sodium ions would be attracted to the cathode, and same for the chloride ions to the anode.
At the cathode side, an electron is given up by the electrode to sodium ions clustering there. But there is the presence of the cage of water
molecules. So, one water molecule is captures the electron instead, and a hydrogen atom and a hydroxide ion is formed. Continue this way, and you get
sodium hydroxide and hydrogen gas at the cathode, and vice versa for the anode.
Now, is this reasoning correct? This too, will apply to the transitions metals with the water as their ligands.
I ask too, what if I electrolyse a solution of tetraamine copper(II) sulpate? The copper ions now instead has ammonia has its ligand. What will happen
now at the cathode.
Thanks for addressing my concerns. (I am sorry, for i cannot find this on the internet)