What happens to DNA in the presence of a chaotropic salt? - (Nov/17/2012 )

I've used 4M Guanidine Hydro Chloride (GuHCl) for Plant RNA Viroid extraction with 25mM EDTA, 0.2M Sodium Acetate (NaAc) (pH 5), 2.5% PVP 40. Could you please tell me ;

How RNA get separated from DNA when using GuHCl?

What is the purpose of adding NaAc in Nucleic Acid Extraction?

What is the purpose of adding NaAc in Nucleic Acid Extraction?
http://www.protocol-online.org/biology-forums/posts/3846.html

Guanidine is a chaotrope, so it essentially denatures the proteins so that they won't stick to the DNA.

Thank you very much memari & bob1