In a class of electrolysis, my instructor told me that Hg forms Na-Hg in the electrolysis of dilute NaCl aqueous solution. For this reason, sodium cations are reduced in the cathode instead of hydronium ions. However, he did not give me any reason for this whatsoever . So, I would like to know why Hg creates amalgam whereas other metals like Pt don't form them ?
If you heat metallic sodium with let’s say gold / silver / mercury / platinum etc.. it will form an amalgam.
I have tried this with a tiny bit of gold some years ago.
I did heat Na in an inert argon atmosphere to several hundred degrees in an quartz tube and drop the gold inside.
It did take only fractions of a second till the amalgam was formed.
The result is a green looking amalgam when it is hot - when it cools down it is a brown solid substance.
Given the fact that gold is a pretty inert substance, I guess that sodium will do the same with Pt, Rh, Ir, Ru, Os, Ag, Hg ...
I guess during electrolysis you have metallic Na formed. I don’t mean junks of Na but Na atoms and some of them may live long enough to amalgamate with the Hg.